Topical Montelukast formulations

ABSTRACT

The present disclosure provides for topical emulsion comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; and about 0.4% to about 4% carbomer; wherein particles comprising the Montelukast in the emulsion have D90 of less than about 50 wherein the Montelukast or pharmaceutically acceptable salt thereof is homogeneously dispersed in the emulsion, and wherein the emulsion has a pH of about 3.0 to about 6.5. The present disclosure also provides a topical gel comprising (a) about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; (b) about 0.2% to about 8% cellulose polymer; and (c) about 80% to about 95% amphiphilic compound; wherein the gel comprises less than 4% water.

FIELD OF THE INVENTION

The present disclosure provides for topical emulsion comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; and about 0.4% to about 4% carbomer; wherein particles comprising the Montelukast in the emulsion have D90 of less than about 50 μm, wherein the Montelukast or pharmaceutically acceptable salt thereof is homogeneously dispersed in the emulsion, and wherein the emulsion has a pH of about 3.0 to about 6.5. The present disclosure also provides a topical gel comprising (a) about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; (b) about 0.2% to about 8% cellulose polymer; and (c) about 80% to about 95% amphiphilic compound; wherein the gel comprises less than 4% water.

BACKGROUND

Atopic dermatitis is an increasingly common pruritic, chronic, inflammatory skin disorder. There has been a striking rise in the incidence of Atopic dermatitis (AD) during the past two decades, which is not simply due to an increased recognition of the disease. Population studies suggest that in most countries, AD now affects at least 10-20% of children at some point during childhood. In particular, higher prevalence has been recorded in urban regions than in rural regions of development countries, and the disease is more common in higher social class groups, suggesting that environmental factors associated with more industrialized and urban living determine expression of AD.

The major function of the skin is to protect the body against physical and chemical injury and to prevent loss of body water and other substances. The stratum corneum (SC) is the outmost layer of the skin which is being continually replaced. By so doing the skin is well adapted to its requirements for repairing damage from wear and tear. However, in Atopic Dermatitis environmental and individual factors interact in a complex manner to induce skin abnormalities and dryness. Application of moisturizers to the skin induces changes in its superficial as well as deep layers. The chemical and physical characteristics of the individual ingredients of the formulation determine the performance of the drug product. Moreover, in topical treatments of dermatological conditions the efficacy is likely to depend on the dosage, where compliance is a great challenge faced in the management of the diseases.

Montelukast sodium exerts challenges when being formulated, including stability challenges and permeation challenges.

SUMMARY OF THE INVENTION

The present disclosure is directed to a topical emulsion and a topical gel that are stable for an extended period of time. In some embodiments, the disclosure is directed to a topical emulsion comprising (a) about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; and (b) about 0.4% to about 4% carbomer; wherein particles comprising the Montelukast in the emulsion have a D90 of less than about 50 μm, wherein the Montelukast or pharmaceutically acceptable salt thereof is homogeneously dispersed in the emulsion, and wherein the emulsion has a pH of about 3.0 to about 6.5.

In some embodiments, the particles comprising the Montelukast in the emulsion have D90 of less than about 40 μm. In some embodiments, the particles comprising the Montelukast in the emulsion have D90 of less than about 20 μm. In some embodiments, the particles comprising the Montelukast in the emulsion have D90 of greater than about 8 μm. In some embodiments, the particles comprising the Montelukast in the emulsion have D90 of about 10 μm to about 14 μm.

In some embodiments, the particles comprising the Montelukast in the emulsion have D50 of less than about 30 μm. In some embodiments, the particles comprising the Montelukast in the emulsion have D50 of less than about 25 μm. In some embodiments, the particles comprising the Montelukast in the emulsion have D50 of less than about 15 μm. In some embodiments, the particles comprising the Montelukast in the emulsion have D50 of less than about 5 μm.

In some embodiments, the particles comprising the Montelukast in the emulsion have D10 of less than about 7 μm.

In some embodiments, the particles comprising the Montelukast in the emulsion have D10 of greater than about 3 μm. In some embodiments, the particles comprising the Montelukast in the emulsion have D10 of about 4 μm to about 6 μm. In some embodiments, the average particle size of the particles does not change greater than 10% over a period of 3 months at 25° C. In some embodiments, the Montelukast in the particles is Montelukast acid Form I. In some embodiments, the emulsion comprises about 4% to about 8% Montelukast.

In some embodiments, the emulsion comprises about 40% to about 70% water. In some embodiments, the emulsion further comprises a penetration enhancer. In some embodiments, the penetration enhancer is DMSO. In some embodiments, the emulsion comprises less than 5% DMSO. In some embodiments, the emulsion comprises less than 3% DMSO.

In some embodiments, the emulsion comprises less than 10% alcohol. In some embodiments, the emulsion comprises less than 5% alcohol. In some embodiments, the emulsion comprises less than 2% C₁-C₅ alcohol.

In some embodiments, the topical emulsion further comprises a preservative, an amphiphilic compound, an emulsifier, a lubricant, or combinations thereof. In some embodiments, the preservative is an antioxidant. In some embodiments, the antioxidant comprises BHT, BHA or combinations thereof.

In some embodiments, the amphiphilic compound comprises, oleyl alcohol, polyoxyglycerides, propylene carbonate, propylene glycol, or combinations thereof. In some embodiments, the amphiphilic compound is propylene glycol. In some embodiments, the emulsifier is a polysorbate. In some embodiments, the lubricant is polypropylene glycol stearyl ether.

In some embodiments, the total impurities in the emulsion are less than 2% after 12 months at 25° C. In some embodiments, the total impurities in the emulsion are less than 1% after 12 months at 25° C. In some embodiments, the total impurities in the emulsion are less than 0.5% after 12 months at 25° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 2% after 12 months at 25° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 1% after 12 months at 25° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 0.5% after 12 months at 25° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 1% after 12 months at 25° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 0.1% after 12 months at 25° C. In some embodiments, the methylstyrene impurity in the emulsion is less than 0.2% after 12 months at 25° C.

In some embodiments, the disclosure provides a method of treating atopic dermatitis comprising administering the topical emulsion of the present disclosure.

In some embodiments, the disclosure is directed to a topical gel. In some embodiments, the disclosure provides a topical gel comprising (a) about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof (b) about 0.2% to about 8% cellulose polymer; and (c) about 80% to about 95% amphiphilic compound; wherein the gel comprises less than 4% water.

In some embodiments, the gel comprises about 4% to about 8% Montelukast.

In some embodiments, the gel comprises less than 1% C₁-C₅ alcohol. In some embodiments, the gel does not contain C₁-C₅ alcohol. In some embodiments, the gel comprises less than 2% water. In some embodiments, the gel comprises less than 1% water. In some embodiments, the gel is anhydrous.

In some embodiments, the gel does not comprise a preservative.

In some embodiments, the cellulose polymer comprises hydroxyethylcellulose and hydroxypropyl methylcellulose. In some embodiments, the cellulose polymer comprises hydroxypropyl methylcellulose. In some embodiments, the cellulose polymer comprises hydroxypropyl cellulose. In some embodiments, the gel comprises about 2% to about 6% cellulose polymer. In some embodiments, the gel comprises about 3% to about 4% cellulose polymer.

In some embodiments, the amphiphilic compound comprises oleyl alcohol, polyoxyglycerides, propylene carbonate, propylene glycol, or combinations thereof. In some embodiments, the amphiphilic compound comprises propylene glycol. In some embodiments, the gel comprises about 85% to about 95% amphiphilic compound.

In some embodiments, total impurities in the gel are less than 0.5% after 3 months at 25° C. In some embodiments, the sulfoxide impurity in the gel is less than 0.5% after 3 months at 25° C. In some embodiments, the cis-isomer impurity in the gel is less than 0.1% after 3 months at 25° C. In some embodiments, the methylstyrene impurity in the gel is less than 0.2% after 3 months at 25° C.

In some embodiments, the disclosure provides a method of treating atopic dermatitis comprising administering the topical gel of the present disclosure.

In some embodiments, the disclosure provides a method of reducing the IGA score in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the IGA score is reduced by at least 5% from placebo.

In some embodiments, the disclosure provides a method of reducing the BSA score in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the BSA score is reduced by at least 5% from placebo.

In some embodiments, the disclosure provides a method of reducing erythema in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the erythema is reduced by at least 5% from placebo.

In some embodiments, the disclosure provides a method of reducing induration in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the induration is reduced by at least 5% from placebo.

In some embodiments, the disclosure provides a method of reducing lichenfication in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the lichenfication is reduced by at least 5% from placebo.

In some embodiments, the disclosure provides a method of reducing pruritus in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the pruritus is reduced by at least 5% from placebo.

In some embodiments, the disclosure provides methods as described herein, wherein the Montelukast formulation is the topical emulsion or the topical gel as described herein.

In some embodiments, the disclosure provides a stable topical formulation comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; wherein the total impurities resulting from the degradation of Montelukast in the composition are less than 2% after 12, 24 or 36 months at 25° C. In some embodiments, a sulfoxide impurity in the stable topical formulation is less than 2% after 12, 24 or 36 months at 25° C. In some embodiments, a cis-isomer impurity in the stable topical formulation is less than 1% after 12, 24 or 36 months at 25° C. In some embodiments, a methylstyrene impurity in the stable topical formulation is less than 0.2% after 12, 24 or 36 months at 25° C. In some embodiments, the Montelukast is homogenously dispersed in the stable topical formulation for at least about 1 month. In some embodiments, the stable topical formulation is a gel. In some embodiments, the stable topical formulation is an emulsion. In some embodiments, the particle size of particles comprising Montelukast in the emulsion have a D90 of less than about 50 μm and greater than 5 In some embodiments, the particle size of particles comprising Montelukast in the emulsion does not change greater than 20% over a period of three months at 25° C.

DETAILED DESCRIPTION

The present disclosure provides for topical formulations of Montelukast or pharmaceutically acceptable salt thereof. In some embodiments, the disclosure provides for a topical emulsion that comprising (a) about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; and (b) about 0.4% to about 4% carbomer; wherein particles comprising the Montelukast in the emulsion have D90 of less than about 50 μm, wherein the Montelukast or pharmaceutically acceptable salt thereof is homogeneously dispersed in the emulsion, and wherein the emulsion has a pH of about 3.0 to about 6.5. Applicant has found that the topical emulsions provided herein are both physically and chemically stable over extended periods of time at room temperature, or at accelerated conditions.

In some embodiments, the disclosure provides for a topical gel comprising (a) about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; (b) about 0.2% to about 8% cellulose polymer; and (c) about 80% to about 95% amphiphilic compound; wherein the gel comprises less than 4% water. Applicant has found that the topical gels provided herein are both physically and chemically stable over extended periods of time at room temperature, or at accelerated conditions.

As used herein, “a” or “an” may mean one or more. As used herein, when used in conjunction with the word “comprising,” the words “a” or “an” may mean one or more than one. As used herein, “another” or “a further” may mean at least a second or more.

Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the method/device being employed to determine the value, or the variation that exists among the study subjects. Typically, the term “about” is meant to encompass approximately or less than 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20% or higher variability, depending on the situation. In some embodiments, one of skill in the art will understand the level of variability indicated by the term “about,” due to the context in which it is used herein. It should also be understood that use of the term “about” also includes the specifically recited value.

The use of the term “or” in the claims is used to mean “and/or,” unless explicitly indicated to refer only to alternatives or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or.”

As used herein, the terms “comprising” (and any variant or form of comprising, such as “comprise” and “comprises”), “having” (and any variant or form of having, such as “have” and “has”), “including” (and any variant or form of including, such as “includes” and “include”) or “containing” (and any variant or form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. It is contemplated that any embodiment discussed in this specification can be implemented with respect to any composition (e.g., formulation, emulsion or gel) or method of the present disclosure. Furthermore, compositions (e.g., formulations, emulsion or gel) of the present disclosure can be used to achieve methods of the present disclosure.

The use of the term “for example” and its corresponding abbreviation “e.g.” (whether italicized or not) means that the specific terms recited are representative examples and embodiments of the disclosure that are not intended to be limited to the specific examples referenced or cited unless explicitly stated otherwise.

As used herein, “between” is a range inclusive of the ends of the range. For example, a number between x and y explicitly includes the numbers x and y, and any numbers that fall within x and y.

As used herein, “D10” is defined as the size value corresponding to cumulative size distribution at 10%, which represents the size of particles below which 10% of the sample lies.

As used herein, “D50” is defined as the size value corresponding to cumulative size distribution at 50%, which represents the size of particles below which 50% of the sample lies.

As used herein, “D90” is defined as the size value corresponding to cumulative size distribution at 90%, which represents the size of particles below which 90% of the sample lies.

As used herein, “formulation stability” refers to chemical stability, physical stability or both chemical and physical stability.

The term Montelukast refers to [R-(E)]-1-[[[1-[3-[2-(7-chloro-2-quinolinyl)-ethenyl]-phenyl]-3-[2-(1-hydroxy-1- methylethyl)phenyl]propyl]thio]methyl]cyclopropane acetic acid (Montelukast) or a pharmaceutically acceptable salt thereof. For simplicity, as used herein, the term Montelukast includes the designated chemical entity as well as, at times, its pharmaceutically acceptable salt.

In some embodiments, the Montelukast is in the form of a salt. Suitable Montelukast salts can include an alkali metal salt such as sodium or potassium, an alkaline earth salt, or an ammonium salt. In some embodiments, the Montelukast can be a free acid. In some embodiments, the Montelukast can be a monosodium salt, as represented as

In some embodiments, the Montelukast is added as a salt or free acid when preparing emulsion or gel formulations, and then become a free acid once in its final dosage form. In some embodiments, the Montelukast crystal particles comprise the free acid form, e.g., Form I.

Topical Emulsion

The present disclosure provides for a topical emulsion comprising Montelukast or pharmaceutically acceptable salt thereof. Montelukast is known to be stable at high pH solutions, e.g. in pH above 7. The present disclosure provides for an emulsion which is compatible with the pH of the skin, i.e., pH of around 3 to 6.5, while keeping Montelukast physically and chemically stable in the emulsion. Additionally, the present disclosure provides an emulsion in which the Montelukast, with a molecular weight of greater 600, is able to achieve skin penetration in an amount to be therapeutically effective. The present disclosure provides a topical emulsion suitable for application to the skin without undue irritation, while maintain the physical stability, chemical stability and efficacy of the Montelukast.

In some embodiments, the disclosure provides a topical emulsion having Montelukast or pharmaceutically acceptable salt thereof of a defined particle size. Applicant has found that, in some embodiments, emulsions comprising the Montelukast particles are physically stable, wherein the particles remain homogeneously dispersed in the topical emulsion, and wherein the average size of Montelukast particles does not change over an extended period of time.

In some embodiments, particles comprising the Montelukast in the emulsion have D90 of less than about 50 μm, less than about 40 μm, less than about 35 μm, less than about 30 μm, less than about 25 μm, less than about 20 μm, or less than about 15 μm. In some embodiments, particles comprising the Montelukast in the emulsion have D50 of less than about 30 μm, less than about 25 μm, less than about 20 μm, less than about 15 μm, or less than about 10 μm. In some embodiments, particles comprising the Montelukast in the emulsion have a D90 of less than about 40 μm and a D50 of less than about 25 μm. D90 less than about 35 μm and a D50 of less than about 25 μm, D90 less than about 30 μm and a D50 of less than about 20 μm, D90 less than about 25 μm and a D50 of less than about 15 μm, or D90 of less than about 20 μm and a D50 of less than about 15 μm.

In some embodiments, particles comprising the Montelukast in the emulsion have D90 of less than about 50 μm and greater than 5 μm, less than about 40 μm and greater than 10 μm, less than about 30 μm and greater than 10 μm, less than about 20 μm and greater than 10 μm. In some embodiments, particles comprising the Montelukast in the emulsion have D50 of less than about 30 μm and greater than 2 μm, less than about 25 μm and greater than 3 μm, less than about 20 μm and greater than 4 μm, less than about 15 μm and greater than 5 μm. In some embodiments, particles comprising the Montelukast in the emulsion have D90 of less than about 50 μm and greater than 8 μm, and a D50 of less than about 30 μm and greater than about 5 μm. In some embodiments, particles comprising the Montelukast in the emulsion have D90 of about 5 μm to 50 μm and a D50 of 2 μm to 30 μm, D90 of about 10 μm to 40 μm and a D50 of about 3 μm to 25 μm, D90 of about 10 μm to 30 μm and a D50 of about 3 μm to 20 μm, D90 of about 10 μm to 20 μm and a D50 of about 5 μm to 10 μm. In some embodiments, the particles comprising the Montelukast in the emulsion have D90 of about 10 μm to 14 μm and a D50 of 7 μm to 11 μm,

In some embodiments, particles comprising the Montelukast in the emulsion have D10 of less than about 20 μm, less than about 15 μm, less than about 12 μm, less than about 10 μm, or less than about 7 μm. In some embodiments, particles comprising the Montelukast in the emulsion have D10 of less than about 7 μm. In some embodiments, particles comprising the Montelukast in the emulsion have D10 greater than about 1 μm, greater than about 2 μm, greater than about 3 μm, greater than about 4 μm, greater than about 5 μm, greater than about 6 μm. In some embodiments, particles comprising the Montelukast in the emulsion have D10 of greater than about 3 μm.

In some embodiments, particles comprising the Montelukast in the emulsion have a particle size distribution as found in Table 1:

TABLE 1 D90 (μm) D50 (μm) D10 (μm) <50 <30 <15  5-50 2-30 1-15  5-40 2-25 1-15  5-30 2-20 1-15 10-25 4-20 1-15 10-20 5-15 1-10

The particles comprising Montelukast are physically stable in the topical emulsion over an extended period of time. The term “physically stable” can refer to particles that remain homogenously dispersed in the topical emulsion for an extended period of time, i.e., the particles do not precipitate. Likewise, the term “physically stable” can refer to particles that remain homogenously dispersed in the topical emulsion for an extended period of time, i.e., the particles do not form aggregates in the emulsion. The term “physically stable” can also refer to topical emulsion in which no phase separation is identified for an extended period of time.

Additionally, the term “physically stable” can refer to particles that remain the same size distribution in the topical emulsion for an extended period of time, i.e., the particles do not further crystalize, agglomerate, dissolve, or otherwise break apart in the emulsion. For example, in some embodiments, the D50 does not change greater than 20%, greater than 15%, greater than 10%, greater than 5%, greater than 2%, or greater than 1% over an extended period of time. In some embodiments, the D90 does not change greater than 20%, greater than 15%, greater than 10%, greater than 5%, greater than 2%, or greater than 1% over an extended period of time. In some embodiments, the average particle size of the particles does not change greater than 20%, greater than 15%, greater than 10%, greater than 5%, greater than 2%, or greater than 1% over an extended period of time.

In some embodiments, the particles comprising Montelukast are physically stable an “extended period of time.” One skilled in the art can appreciate the benefits of a topical emulsion that is stable during manufacturing, transport and storage of the topical emulsion before use. In some embodiments, extended period of time can include for at least one week, at least two weeks, at least three weeks, at least one month, at least two months, three months, at least four months, at least six months, at least one year or at least two years.

The skilled artisan can appreciate that physical stability can be affected by several factors, e.g., temperature, humidity, oxidation, sunlight, etc. As used herein, physical stability is determined using standard conditions or accelerated conditions in a sealed container not subject to light degradation or oxidation.

In some embodiments, the particle size of particles in the emulsion comprising Montelukast in the emulsion does not change greater than 20% over a period of three months at 25° C., six months at 25° C., nine months at 25° C., or one year at 25° C. In some embodiments, the particle size in the emulsion does not change greater than 10% over a period of three months at 25° C., six months at 25° C., nine months at 25° C., or one year at 25° C. In some embodiments, the particle size in the emulsion does not change greater than 5% over a period of three months at 25° C., six months at 25° C., nine months at 25° C., or one year at 25° C. In some embodiments, the particle size in the emulsion does not change greater than 1% over a period of three months at 25° C., six months at 25° C., nine months at 25° C., or one year at 25° C.

In some embodiments, the particle size of particles comprising Montelukast in the emulsion does not change greater than 20% over a period of three months at 37° C., six months at 37° C., nine months at 37° C., or one year at 37° C. In some embodiments, the particle size in the emulsion does not change greater than 10% over a period of three months at 37° C., six months at 37° C., nine months at 37° C., or one year at 37° C. In some embodiments, the particle size in the emulsion does not change greater than 5% over a period of three months at 37° C., six months at 37° C., nine months at 37° C., or one year at 37° C. In some embodiments, the particle size in the emulsion does not change greater than 1% over a period of three months at 37° C., six months at 37° C., nine months at 37° C., or one year at 37° C.

The Montelukast particles can be formed by various methods. In some embodiments, the particles are formed in-situ in the emulsions. Alternatively, in some embodiments, the particles of Montelukast or pharmaceutically acceptable salt thereof are obtained by milling, screening, or other methods known in the art. Methods of determining particle size are known to the skilled artisan and can include particle size analyzer, light microscopy, and/or electron microscopy.

One of skill in the art can appreciate the in-situ formation of particles comprising Montelukast. In some embodiments, greater than 50% of the Montelukast in the emulsion is in particles, with the remaining less than 50% being in solution. In some embodiments, greater than 55%, greater than 65%, greater than 70%, greater than 75%, greater than 80% or greater than 85% of the Montelukast in the emulsion is in particles. In some embodiments, about 70% to about 95% of the Montelukast in the emulsion is in particles, with the remaining 5% to 30% being in solution. In some embodiments, about 80% to about 95% of the Montelukast in the emulsion is in particles, with the remaining 5% to 20% being in solution.

In some embodiments, the Montelukast or pharmaceutically acceptable salt thereof is chemically stable in the emulsion. The term “chemically stable” indicates the Montelukast does not appreciably degrade to form impurities. Various degradation impurities are known in the art, and include

1. a sulfoxide impurity: 1-[((RS)[1-[3-[(E)-2-(7-Chloroquinolin-2-yl)ethenyl)phenyl)-3-[2-(1-hydroxy-1- methylethyl)phenyl)propyl]sylfinyl]methyl]clyclopropyl]acetic acid;

2. a diol impurity: 2-(2-(3-(S)-(3(E)-(2-(7-Chloro-2-quinolinyl)-ethenyl)phenyl)-3-hydroxypropyl)phenyl)-2-propanol;

3. a methyl styrene impurity: [1-[[[(1R)-1-[3-[(E)-(7-Chloroquinolin-2-yl)ethenyl]phenyl]-3-[2-(1- methylethenyl)phenyl]propyl]sulfanyl]methyl]cyclopropyl]acetic acid (USP imp F);

4. a cis-isomer impurity: [1-[[[(1R)-1-[3-[(Z)-2-(7-Chloroquinolin-2-yl)ethenyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]sulfanyl]methyl]cyclopropyl]acetic acid;

5. a Michael adduct impurity (1): 1-[[((1R)-1-[3-[(1R)-1-[[[1-(Carboxymethyl) cyclopropyl]methyl]sulfanyl]-2-(7-chloroquinolin-2-yl)ethyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]sulfonyl]methyl]cyclopropyl]acetic acid;

6. a Michael adduct impurity (2): 1-[[((1R)-1-[3-[(1S)-1-[[[1-(Carboxymethyl) cyclopropyl]methyl]sulfanyl]-2-(7-chloroquinolin-2-yl)ethyl]phenyl]-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]sulfonyl]methyl]cyclopropyl]acetic acid;

7. a methyl ketone impurity: [1-({((1R)-3-(2-acetylphenyl)-1-[3-[€-2-(7-chloroquinolin-2-yl)ethenyl)phenyl]propyl]sulfanyl]methyl]cyclopropyl]acetic acid;

As used herein, the term “total impurities” refers to the combined amount of a sulfoxide impurity, a methyl styrene impurity, and a cis-isomer impurity, as well as all other degradation impurities found in the topical emulsion. In some embodiments, the total impurities in the emulsion are less than 2% after 3 months at 25° C. In some embodiments, the total impurities in the emulsion are less than 1% after 3 months at 25° C. In some embodiments, the total impurities in the emulsion are less than 0.5% after 3 months at 25° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 2% after 3 months at 25° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 1% after 3 months at 25° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 0.5% after 3 months at 25° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 1% after 3 months at 25° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 0.5% after 3 months at 25° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 0.1% after 3 months at 25° C. In some embodiments, the methylstyrene impurity in the emulsion is less than 0.2% after 3 months at 25° C. Methods of determining impurities are well established, and can include conventional techniques such as HPLC.

The impurities can be measured after a designated period of time at standard room temperature (RT) conditions (25° C., 60% humidity), intermediate (INT) conditions (30° C., 65% humidity), and/or accelerated (ACC) conditions (40° C., 75% humidity).

In some embodiments, the total impurities in the emulsion are less than 2% after 6 months or 1 year at 25° C. In some embodiments, the total impurities in the emulsion are less than 1% after 6 months or 1 year at 25° C. In some embodiments, the total impurities in the emulsion are less than 0.5% after 6 months or 1 year at 25° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 2% after 6 months or 1 year at 25° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 1% after 6 months or 1 year at 25° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 0.5% after 6 months or 1 year at 25° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 1% after 6 months or 1 year at 25° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 0.1% after 6 months or 1 year at 25° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 0.05% after 6 months or 1 year at 25° C. In some embodiments, the methylstyrene impurity in the emulsion is less than 0.2% after 6 months or 1 year at 25° C. In some embodiments, the methylstyrene impurity in the emulsion is less than 0.1% after 6 months or 1 year at 25° C.

In some embodiments, the total impurities in the emulsion are less than 2% after 3 months at 30° C. In some embodiments, the total impurities in the emulsion are less than 1% after 3 months at 30° C. In some embodiments, the total impurities in the emulsion are less than 0.5% after 3 months at 30° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 2% after 3 months at 30° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 1% after 3 months at 30° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 0.5% after 3 months at 30° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 1% after 3 months at 30° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 0.1% after 3 months at 30° C. In some embodiments, the methylstyrene impurity in the emulsion is less than 0.2% after 3 months at 30° C.

In some embodiments, the total impurities in the emulsion are less than 2% after 6 months or 1 year at 30° C. In some embodiments, the total impurities in the emulsion are less than 1% after 6 months or 1 year at 30° C. In some embodiments, the total impurities in the emulsion are less than 0.5% after 6 months or 1 year at 30° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 2% after 6 months or 1 year at 30° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 1% after 6 months or 1 year at 30° C. In some embodiments, the sulfoxide impurity in the emulsion is less than 0.5% after 6 months or 1 year at 30° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 1% after 6 months or 1 year at 30° C. In some embodiments, the cis-isomer impurity in the emulsion is less than 0.1% after 6 months or 1 year at 30° C. In some embodiments, the methylstyrene impurity in the emulsion is less than 0.2% after 6 months or 1 year at 30° C.

In some embodiments, the total impurities in the emulsion are less than 2% after 3 months under accelerated conditions. In some embodiments, the total impurities in the emulsion are less than 1% after 3 months under accelerated conditions. In some embodiments, the total impurities in the emulsion are less than 0.5% after 3 months under accelerated conditions. In some embodiments, the sulfoxide impurity in the emulsion is less than 2% after 3 months under accelerated conditions. In some embodiments, the sulfoxide impurity in the emulsion is less than 1% after 3 months under accelerated conditions. In some embodiments, the sulfoxide impurity in the emulsion is less than 0.5% after 3 months under accelerated conditions. In some embodiments, the cis-isomer impurity in the emulsion is less than 1% after 3 months under accelerated conditions. In some embodiments, the cis-isomer impurity in the emulsion is less than 0.1% after 3 months under accelerated conditions. In some embodiments, the methylstyrene impurity in the emulsion is less than 0.2% after 3 months under accelerated conditions.

In some embodiments, the total impurities in the emulsion are less than 2% after 6 months or 1 year under accelerated conditions. In some embodiments, the total impurities in the emulsion are less than 1% after 6 months or 1 year under accelerated conditions. In some embodiments, the total impurities in the emulsion are less than 0.5% after 6 months or 1 year under accelerated conditions. In some embodiments, the sulfoxide impurity in the emulsion is less than 2% after 6 months or 1 year under accelerated conditions. In some embodiments, the sulfoxide impurity in the emulsion is less than 1% after 6 months or 1 year under accelerated conditions. In some embodiments, the sulfoxide impurity in the emulsion is less than 0.5% after 6 months or 1 year under accelerated conditions. In some embodiments, the cis-isomer impurity in the emulsion is less than 1% after 6 months or 1 year under accelerated conditions. In some embodiments, the cis-isomer impurity in the emulsion is less than 0.1% after 6 months or 1 year under accelerated conditions. In some embodiments, the methylstyrene impurity in the emulsion is less than 0.2% after 6 months or 1 year under accelerated conditions.

The Montelukast of the emulsion of present disclosure can be in an amorphous form, or a crystalline form. In some embodiments, the Montelukast in the particles in the emulsion is in a polymorphic crystalline form. For example, in some embodiments, the Montelukast is Montelukast acid Form I as described in US 2005/0187243, incorporated herein in its entirety.

The topical emulsion as described herein comprises (a) Montelukast or pharmaceutically acceptable salt thereof, and (b) a carbomer at specified percentages. As used throughout, a percentage, i.e., “%”, of a component of the emulsion refers to the weight percent, i.e., w/w.

The topical emulsions provided herein can comprise various concentration of Montelukast or pharmaceutically acceptable salt thereof. In some embodiments, the topical emulsion comprises about 0.05% to about 20%, about 1% to about 15%, about 2% to about 12%, about 3% to about 10%, about 4% to about 8%, about 5% to about 7% or about 6% Montelukast or pharmaceutically acceptable salt thereof. In some embodiments, the topical emulsion comprises about 3% to about 8% Montelukast or pharmaceutically acceptable salt thereof.

The topical emulsions provided herein can comprise various concentration of carbomer. In some embodiments, the topical emulsion comprises about 0.4% to about 5% carbomer, about 0.5% to about 4% carbomer, about 0.8% to about 3% carbomer, or about 1% to about 2% carbomer. While not being bound by any particular theory, in some embodiments the carbomer can lower the pH of the emulsion to provide the free acid form of Montelukast, which can increase penetration of the Montelukast into the skin.

Various carbomers are known in the art. The term carbomer refers to synthetic high-molecular weight polymers primarily made from acrylic acid. Carbomers may be homopolymers of acrylic acid, or copolymers with acrylic acid and C₁₀-C₃₀ alkyl acrylate crosslinked with allyl ether of pentaerythritol, allyl ether of sucrose, or allyl ether of propylene. Carbomer homopolymers can comprise acrylic acid crosslinked with allyly sucrose or allyl pentaerythritol. Carbomer codes (e.g., 910, 934, 940, 941, and 934P) are an indication of molecular weight and the specific components of the polymer. One tradename for carbomers is CARBOPOL® (Lubrizol Corporation, Wickliffe, OH).

Suitable carbomers can include, but are not limited to, the commercially available carbomers in Table 2, manufactured by Lubrizol Corporation.

TABLE 2 Viscosity, cP Carbopol ® Polymer Polymerization Solvent Carbomer Product Type (0.5 wt % at pH 7.5) 71G NF Ethyl Acetate Homopolymer  4,000-11,000 971P NF Ethyl Acetate Homopolymer  4,000-11,000 974P NF Ethyl Acetate Homopolymer 29,400-39,400 980 NF Cosolvent¹ Homopolymer 40,000-60,000 981 NF Cosolvent¹ Homopolymer  4,000-10,000 5984 EP C5984 EPosolvent¹ Homopolymer 30,500-39,400 ETD 2020 NF Cosolvent¹ Interpolymer  47,000-77,0002 Ultrez 10 NF Cosolvent¹ Interpolymer 45,000-65,000 934 NF Benzene Homopolymer 30,500-39,400 934P NF Benzene Homopolymer 29,400-39,400 940 NF Benzene Homopolymer 40,000-60,000 941 NF Benzene Homopolymer  4,000-10,000 1342 NF Benzene Copolymer  9,500-26,5002 ¹Cosolvent system made using cyclohexane and ethyl acetate Carbopol homopolymers are polymers of acrylic acid crosslinked with allyl sucrose or allyl pentaerythritol Carbopol copolymers are polymers of acrylic acid and C10-C30 alkyl acrylate crosslinked with allyl pentaerythritol Carbopol interpolymers are a carbomer homopolymer or copolymer that contains a block copolymer of polyethylene glycol and a long chain alkyl acid ester

In some embodiments, the carbomer is Carbopol® 974P NF, Carbopol® 934P NF, Carbopol® 971P NF, Carbopol® 934 NF. In some embodiments, the carbomer is Carbopol® 974P NF. (Homopolymer Type B, NF).

In some embodiments, the carbomer is a Carbopol®. In some embodiments, the topical emulsion comprises about 0.4% to about 5% Carbopol®, about 0.5% to about 4% Carbopol®, about 0.8% to about 3% Carbopol®, or about 1% to about 2% Carbopol®.

In some embodiments, the topical emulsion comprises water. In some embodiments, the water is about 30% to about 80%, about 40% to about 70%, about 45% to about 65%, or about 50% to 60% of the emulsion.

The pH of the topical emulsion can be about 3.0 to about 6.5, about 3.5 to about 6.5, about 3.5 to about 6.0, or about 4 to about 6. At this pH range, some or all of the Montelukast can be in its free acid form. In some embodiments, the pH of the topical emulsion can be between about 3.0 to about 6.0, about 4.5 to about 6, about 4 to about 5.5, about 4.5 to about 5.5, or about 5 to about 6. Various means of adjusting the pH are known in the art, and can include the additional of acids or bases to achieve the desired pH. In some embodiments, a strong acid, e.g., hydrochloric acid, is not used to adjust the pH of the emulsion.

In some embodiments, the topical emulsion can comprise a penetration enhancer. Suitable penetration enhances are known in the art and can be used with the present invention. Some examples of penetration enhancers include, but are not limited to, polyols and esters, including polyethylene glycol, polyethylene glycol monolaurate, and butanediol; sulfoxides, including dimethylsulfoxide (DMSO) and decylmethylsulfoxide; ethers, including diethylene glycol monoethyl ether (e.g., Transcutol®P) and diethylene glycol monomethyl ether; fatty acids, including lauric acid, oleic acid, and valeric acid; fatty acid esters, including isopropyl myristate, isopropyl palmitate, methyl propionate, and ethyl oleate; nitrogenous compounds including urea, dimethyl acetamide, dimethylformamide 2-pyrrolidone, ethanolamine, methyl-2-pyrrolidone, diethanolamine, and triethanolamine; terpenes; alkanones; organic acids, including salicylic acid, citric acid, and succinic acid; and any mixtures thereof.

Various concentrations of penetration enhancers can be used. In some embodiments, the penetration enhancer is about 0.01% to about 10%, about 0.1% to about 10%, about 1% to about 10% or about 2% to about 8% of the emulsion.

In some embodiments, the penetration enhancer is DMSO. In some embodiments, the amount of DMSO in the topical emulsion is limited, as DMSO in some instances can cause irritation to the skin. Thus, in some embodiments, the topical emulsion comprises less than 5% DMSO or less than 3% DMSO.

In some instances, the topical emulsion comprises an alcohol. In some embodiments, the alcohol can cause irritation when applied to the skin, e.g., in some embodiments with C₁-C₅ alcohol. Thus, in some embodiments, the topical emulsion comprises less than 20% alcohol, less than 15% alcohol, less than 10% alcohol, or less than 5% alcohol. In some embodiments, the topical emulsion comprises less than 20% C₁-C₅ alcohol, less than 15% C₁-C₅ alcohol, less than 10% C₁-C₅ alcohol, less than C₁-C₅ alcohol, less than 2% C₁-C₅ alcohol, less than 1% C₁-C₅ or no C₁-C₅ alcohol. In some embodiments, the C₁-C₅ alcohol can refer to methanol, ethanol, propanol, iso-propanol, butanol, iso-butanol, or pentanol, etc.

In some embodiments, the topical emulsion further comprises a preservative, an amphiphilic compound, an emulsifier, a lubricant, or combinations thereof.

In some embodiments, the preservative can be an antioxidant. In some embodiments, the antioxidant is butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT), or combinations thereof. In some embodiments, the preservative can include a paraben such as a methyl paraben or propyl paraben. The preservative can be about 0.01% to about 10% by weight, about 0.05% to about 5% by weight, about 0.1% to about 1% by weight, about 0.1% to about 0.5% by weight, of the topical emulsion.

In some embodiments, the topical emulsion comprises an amphiphilic compound. In some embodiments, the amphiphilic compound comprises oleyl alcohol, polyoxyglycerides, propylene carbonate, propylene glycol, or combinations thereof. In some embodiments, the amphiphilic compound is propylene glycol.

Various concentrations of amphiphilic compounds can be in the topical formulation. In some embodiments, the amphiphilic compound is about 1% to about 30%, about 2% to about 25%, about 5% to about 25%, or about 10% to about 20% of the topical emulsion. In some embodiments, the amphiphilic compound is propylene glycol, and the propylene glycol is about 1% to about 30%, about 2% to about 25%, about 5% to about 25%, or about 10% to about 20% of the topical emulsion.

In some embodiments, the topical emulsion comprises an emulsifier. Suitable emulsifiers for dermatological applications are known in the art. In some embodiments, the emulsifier can be Poloxamer188/polysorbate 20, Silicone Glycerol, polysorbate (e.g., polysorbate 20, polysorbate 40, polysorbate 60 or polysorbate 80). In some embodiments, the emulsifier is a polysorbate. In some embodiments, the emulsifier is a polysorbate 80. In some embodiments, the emulsifier is a polysorbate 60. In some embodiments, the emulsifier is a polysorbate 40.

In some embodiments, the emulsifier is about 0.01% to about 15%, about 0.05% to about 10%, about 0.1% to about 10%, or about 1% to about 5% of the topical emulsion. In some embodiments, the emulsifier is a polysorbate, and the polysorbate is about 0.01% to about 15%, about 0.05% to about 10%, about 0.1% to about 10%, or about 1% to about 5% of the topical emulsion.

In some embodiments, the topical emulsion comprises a lubricant. Suitable lubricants for dermatological applications are known in the art. In some embodiments, the lubricant can include polypropylene glycol (PPG) stearyl ether, Sodium Hyaluronate, Cyclomethicone and Dimethicone 5225C, Cyclomethicone, polypropylene glycol-15 stearyl ether, or combinations thereof. In some embodiments, the lubricant can include polypropylene glycol (PPG) stearyl ether, e.g., PPG-15 stearyl ether.

In some embodiments, the emulsions comprising a carbomer as provided herein have a smaller globule size relative to previous Montelukast formulations. While not being bound by any theory, in some embodiments, emulsions comprising a smaller globule size are more stable relative to emulsions comprising a larger globule size. For example, in some embodiments, the smaller globule size may contribute to the physical stability of products, e.g., Montelukast. See, e.g., Mohsin et al., Tropical J. Pharma. Research, 15(6): 1115-1121 (2016). In some embodiments, a small globule size prevents the globule coalescence and sedimentation against gravitational force.

Thus, in some embodiments, the disclosure provides a method of stabilizing a Montelukast formulation, comprising adding a carbomer to the formulation in an amount sufficient to decrease the globule size to less than about 200 μm, less than about 100 μm, less than about 50 μm, less than about 25 μm or less than about 20 μm.

As used herein, determinations of globule size are as described in the Example section herein. One of skill in the art will appreciate that globule size in a single emulsion sample can vary. Thus, in some embodiments, any reference to globule size can include a “maximum globule size,” i.e., the size of the largest globule measured in the microscope field of view for an emulsion sample. In some embodiments, the maximum globule size is the size of the largest globule measured in one microscopic field, or two or more microscopic fields, e.g., three, four, five, six, seven, eight, nine or ten microscopic fields in an emulsion sample. In some embodiments, the term maximum globule size can refer to the average of the largest globule measured in two or more microscopic fields, e.g., three, four, five, six, seven, eight, nine or ten microscopic fields in an emulsion sample.

In some embodiments, the emulsion has a maximum globule size of less than about 200 μm, less than about 150 μm, less than about 100 μm, less than about 75 μm, less than about 50 μm, less than about 25 μm, or less than about 20 μm. In some embodiments, the emulsion has a maximum globule size of about 1 μm to about 100 μm, about 1 μm to about 50 μm, about 1 μm to about 25 μm or about 1 μm to about 20 μm. In some embodiments, the emulsion has a maximum globule size of about 1 μm to about 15 μm, about 2 μm to about 12 μm, about 3 μm to about 10 μm, or about 5 μm to about 10 μm.

Topical Gel

The present disclosure provides for a topical gel comprising Montelukast or pharmaceutically acceptable salt thereof. The present disclosure provides a gel in which Montelukast or any salt thereof, with a molecular weight of about 600 g/mol, is able to achieve skin penetration in an amount to be therapeutically effective, without the use of solvents, such as C₁-C₅ alcohols, that are known to irritate the skin. The present disclosure provides a topical gel suitable for application to the skin without undue irritation, while maintaining the physical stability, chemical stability and efficacy of the Montelukast.

In some embodiments, the disclosure provides for a topical gel comprising Montelukast or pharmaceutically acceptable salt thereof having little or no water present. Applicant has found a topical gel in which the Montelukast remains stable over an extended period of time, while still allowing for topical penetration of Montelukast within the skin. The present disclosure also provides for a topical gel formulation with little or no water in which the Montelukast does not precipitate when stored for an extended period of time.

In some embodiments, the disclosure provides for a topical gel comprising (a) about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; (b) about 0.2% to about 8% cellulose polymer; and (c) about 80% to about 95% amphiphilic compound; wherein the gel comprises less than 4% water.

The topical gel as described herein comprises (a) Montelukast or pharmaceutically acceptable salt thereof, and (b) a cellulose polymer, and (c) an amphiphilic compound at specified percentages. As used throughout, a percentage, i.e., “%”, of a component of the gel refers to the weight percent, i.e., w/w.

The topical gel provided herein can comprise various concentration of Montelukast or pharmaceutically acceptable salt thereof. In some embodiments, the topical gel comprises about 0.05% to about 20%, about 1% to about 15%, about 2% to about 12%, about 3% to about 10%, about 4% to about 8%, about 5% to about 7% or about 6% Montelukast or pharmaceutically acceptable salt thereof. In some embodiments, the topical gel comprises about 3% to about 8% Montelukast or pharmaceutically acceptable salt thereof.

In some instances, the topical gel comprises little or no alcohol. In some embodiments, the alcohol can cause irritation when applied to the skin, e.g., in some embodiments with C₁-C₅ alcohol. Thus, in some embodiments, the topical gel comprises less than 10% alcohol, less than 5% alcohol, less than 2% alcohol, or less than 1% alcohol or no alcohol, i.e., alcohol free. In some embodiments, the topical gel comprises less than 10% C₁-C₅ alcohol, less than 5% C₁-C₅ alcohol, less than 2% C₁-C₅ alcohol, less than 1% C₁-C₅ alcohol, less than 0.5% C₁-C₅ alcohol, less than 0.1% C₁-C₅ or no C₁-C₅ alcohol. In some embodiments, the topical gel comprises no C₁-C₅ alcohol. In some embodiments, the C₁-C₅ alcohol can refer to methanol, ethanol, propanol, iso-propanol, butanol, iso-butanol, or pentanol, etc.

The present disclosure provides for a topical Montelukast gel that is substantially free of water. In some embodiments, a gel comprising reduced amounts of water can provide increased stability of the gel and the Montelukast, providing for longer storage times. In some embodiments, the topical gel comprises less than 2% water. In some embodiments, the gel comprises less than 1% water. In some embodiments, the gel is anhydrous.

In some embodiments, the topical gel provided herein does not comprise a preservative. Applicant found that the gel formulations as disclosed was chemically stable even in the absent of a preservative. Additionally, the presence of a preservative, such as an antioxidant BHA, propyl gallate, alpha tocopherol, ascorbic acid, and their combinations unexpectedly caused increased degradation of Montelukast. Thus, in some embodiments, the disclosure provides a topical gel, wherein the gel does not comprise a preservative, or a highly reduced amount of preservative. In some embodiments, the disclosure provides a topical gel, wherein the gel does not comprise a BHA, propyl gallate, alpha tocopherol, ascorbic acid, and their combinations, or a highly reduced amount of BHA, propyl gallate, alpha tocopherol, ascorbic acid, and their combinations.

The present disclosure provides for a topical gel comprising Montelukast and a cellulose polymer. Cellulose polymers suitable for the topical gel disclosed herein include, but are not limited to, ethyl cellulose, methyl cellulose, propyl cellulose, butyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxybutyl cellulose, hydroxymethyl propyl cellulose, hydroxyethyl propyl cellulose, hydroxypropyl methyl cellulose, or hydroxypropyl ethyl cellulose. Various derivatives of cellulose polymers are known in the art, and can comprise different average number of substituted hydroxyl groups per glucose unit, referred to as the degree of substitution (DS). hydroxy. Complete substitution would provide a DS of 3. Because the hydroxypropyl group added contains a hydroxyl group, this can also be etherified during preparation of HPC. When this occurs, the number of moles of hydroxypropyl groups per glucose ring, moles of substitution (MS), can be higher than 3.

Because cellulose can be crystalline, cellulose polymers comprising hydroxyl groups generally have an MS about 4 in order to reach a good solubility in water. Cellulose polymers can comprise a combination of hydrophobic and hydrophilic groups, so they have a lower critical solution temperature (LCST), e.g., at 45° C. In some embodiments, at temperatures below the LCST, the cellulose polymer is readily soluble in water; above the LCST, cellulose is not soluble. In some embodiments, the cellulose polymers have a LCST suitable for dermatological use.

In some embodiments, the cellulose polymer comprises hydroxyethylcellulose and hydroxypropyl methylcellulose. In some embodiments, the cellulose polymer is hydroxypropyl methylcellulose. In some embodiments, the cellulose polymer is hydroxypropylcellulose.

Various amounts of cellulose polymers can be used in the topical gels of the present disclosure. In some embodiments, the topical gel comprises less than about 15%, less than about 10%, less than about 8%, or less than about 6% cellulose polymer. In some embodiments, the topical gel comprises about 0.5% to about 15%, about 0.5% to about 10%, about 0.5% to about 8%, or about 0.5% to about 6% cellulose polymer. In some embodiments, the topical gel comprises about 1% to about 10%, about 2% to about 6%, or about 3% to about 4% cellulose polymer.

In some embodiments, the cellulose polymer is ethyl cellulose or hydroxypropyl cellulose, wherein the topical gel comprises less than about 15%, less than about 10%, less than about 8%, or less than about 6% ethyl cellulose or hydroxypropyl cellulose. In some embodiments, the topical gel comprises about 0.5% to about 15%, about 0.5% to about 10%, about 0.5% to about 8%, or about 0.5% to about 6% ethyl cellulose or hydroxypropyl cellulose. In some embodiments, the topical gel comprises about 1% to about 10%, about 2% to about 6%, or about 3% to about 4% ethyl cellulose or hydroxypropyl cellulose. In some embodiments, the topical gel comprises about 2% to about 6% ethyl cellulose or hydroxypropyl cellulose.

In some embodiments, the topical gel comprises an amphiphilic compound. In some embodiments, the amphiphilic compound in the topical gel comprises oleyl alcohol, polyoxyglycerides, propylene carbonate, propylene glycol, or combinations thereof. In some embodiments, the amphiphilic compound in the topical gel is propylene glycol.

Various concentrations of amphiphilic compounds can be used with the topical gel. In some embodiments, the amphiphilic compound in the topical gel is about 60% to about 98%, about 70% to about 96%, about 75% to about 95%, or about 80% to about 95% of the topical gel. In some embodiments, the amphiphilic compound in the topical gel is about 85% to about 95% of the topical gel. In some embodiments, the amphiphilic compound in the topical gel is propylene glycol, and the propylene glycol is about 60% to about 98%, about 70% to about 96%, about 75% to about 95%, about 80% to about 95% or about 85% to about 95% of the topical gel.

Applicant has found that the topical gel described in the present disclosure provides for a chemically stable formulation, wherein the topical gel has reduced impurities over an extended period of time. The term “chemically stable” indicates the Montelukast does not appreciably degrade to form impurities in the topical gel. Various degradation impurities are known in the art, and include (a) a sulfoxide impurity, (b) a diol impurity, (c) a methyl styrene impurity, (d) a cis-isomer impurity. (e) a Michael adduct impurity (1), (f) a Michael adduct impurity (2), and (g) a methyl ketone impurity.

As used herein, the term “total impurities” refers to the combined amount of a sulfoxide impurity, a methyl styrene impurity, and a cis-isomer impurity and other degradation impurities found in the topical gel. In some embodiments, the total impurities in the gel are less than 2% after 3 months at 25° C. In some embodiments, the total impurities in the gel are less than 1% after 3 months at 25° C. In some embodiments, the total impurities in the gel are less than 0.5% after 3 months at 25° C. In some embodiments, the sulfoxide impurity in the gel is less than 2% after 3 months at 25° C. In some embodiments, the sulfoxide impurity in the gel is less than 1% after 3 months at 25° C. In some embodiments, the sulfoxide impurity in the gel is less than 0.5% after 3 months at 25° C. In some embodiments, the cis-isomer impurity in the gel is less than 1% after 3 months at 25° C. In some embodiments, the cis-isomer impurity in the gel is less than 0.1% after 3 months at 25° C. In some embodiments, the methylstyrene impurity in the gel is less than 0.2% after 3 months at 25° C.

In some embodiments, the total impurities in the gel are less than 2% after 6 months or 1 year at 25° C. In some embodiments, the total impurities in the gel are less than 1% after 6 months or 1 year at 25° C. In some embodiments, the total impurities in the gel are less than 0.5% after 6 months or 1 year at 25° C. In some embodiments, the sulfoxide impurity in the gel is less than 2% after 6 months or 1 year at 25° C. In some embodiments, the sulfoxide impurity in the gel is less than 1% after 6 months or 1 year at 25° C. In some embodiments, the sulfoxide impurity in the gel is less than 0.5% after 6 months or 1 year at 25° C. In some embodiments, the cis-isomer impurity in the gel is less than 1% after 6 months or 1 year at 25° C. In some embodiments, the cis-isomer impurity in the gel is less than 0.1% after 6 months or 1 year at 25° C. In some embodiments, the cis-isomer impurity in the gel is less than 0.05% after 6 months or 1 year at 25° C. In some embodiments, the methylstyrene impurity in the gel is less than 0.2% after 6 months or 1 year at 25° C. In some embodiments, the methylstyrene impurity in the gel is less than 0.1% after 6 months or 1 year at 25° C.

In some embodiments, the total impurities in the gel is less than 2% after 3 months at 37° C. In some embodiments, the total impurities in the gel is less than 1% after 3 months at 37° C. In some embodiments, the total impurities in the gel are less than 0.5% after 3 months at 37° C. In some embodiments, the sulfoxide impurity in the gel is less than 2% after 3 months at 37° C. In some embodiments, the sulfoxide impurity in the gel is less than 1% after 3 months at 37° C. In some embodiments, the sulfoxide impurity in the gel is less than 0.5% after 3 months at 37° C. In some embodiments, the cis-isomer impurity in the gel is less than 1% after 3 months at 37° C. In some embodiments, the cis-isomer impurity in the gel is less than 0.1% after 3 months at 37° C. In some embodiments, the methylstyrene impurity in the gel is less than 0.2% after 3 months at 37° C.

In some embodiments, the total impurities in the gel are less than 2% after 6 months or 1 year at 37° C. In some embodiments, the total impurities in the gel are less than 1% after 6 months or 1 year at 37° C. In some embodiments, the total impurities in the gel are less than 0.5% after 6 months or 1 year at 37° C. In some embodiments, the sulfoxide impurity in the gel is less than 2% after 6 months or 1 year at 37° C. In some embodiments, the sulfoxide impurity in the gel is less than 1% after 6 months or 1 year at 37° C. In some embodiments, the sulfoxide impurity in the gel is less than 0.5% after 6 months or 1 year at 37° C. In some embodiments, the cis-isomer impurity in the gel is less than 1% after 6 months or 1 year at 37° C. In some embodiments, the cis-isomer impurity in the gel is less than 0.1% after 6 months or 1 year at 37° C. In some embodiments, the methylstyrene impurity in the gel is less than 0.2% after 6 months or 1 year at 37° C.

Stable Topical Formulations

The disclosure herein provides for formulations that are both physically and chemically stable as described previously. In some embodiments, the disclosure provides a stable topical formulation comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; wherein the total impurities resulting from the degradation of Montelukast in the composition are less than 2% after 12, 24 or 36 months at 25° C. and 60% humidity. In some embodiments, a sulfoxide impurity in the stable topical formulation is less than 2% after 12, 24 or 36 months at 25° C. and 60% humidity. In some embodiments, a cis-isomer impurity in the stable topical formulation is less than 1% after 12, 24 or 36 months at 25° C. and 60% humidity. In some embodiments, a methylstyrene impurity in the stable topical formulation is less than 0.2% after 12, 24 or 36 months at 25° C. and 60% humidity.

In some embodiments, the disclosure provides a stable topical formulation comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; wherein the total impurities resulting from the degradation of Montelukast in the composition are less than 1% after 6 months at 40° C. and 75% humidity. In some embodiments, a sulfoxide impurity in the stable topical formulation is less than 2% after 6 months at 40° C. and 75% humidity. In some embodiments, a cis-isomer impurity in the stable topical formulation is less than 1% after 6 months at 40° C. and 75% humidity. In some embodiments, a methylstyrene impurity in the stable topical formulation is less than 0.2% after 6 months at 40° C. and 75% humidity.

In some embodiments, the Montelukast is homogenously dispersed in the stable topical formulation for at least about 1 month. In some embodiments, the stable topical formulation is a gel. In some embodiments, the stable topical formulation is an emulsion. In some embodiments, the particle size of particles comprising Montelukast in the emulsion have a D90 of less than about 50 μm and greater than 5 μm, In some embodiments, the particle size of particles comprising Montelukast in the emulsion does not change greater than 20% over a period of three months at 25° C.

Methods of Treatment

The topical gel and topical emulsion described herein provide for stable formulations which are suitable for topical penetration of Montelukast into the skin. Thus, the present disclosure provides a formulation (e.g., emulsion or gel) suitable for topical administration for any condition in which Montelukast is effective for treatment, e.g., atopic dermatitis (i.e., atopic eczema), infantile atopic eczema, flexural eczema, prurigo Besnier, allergic eczema, and neurodermatitis. In some embodiments, the present disclosure provides a method for treating atopic dermatitis comprising administering the topical emulsion described herein. In some embodiments, the present disclosure provides a method for treating any inflammatory skin disease such as atopic dermatitis comprising administering the topical gel or emulsion described herein. In some embodiments, the present disclosure provides a method for treating infantile atopic eczema, flexural eczema, prurigo Besnier, allergic eczema, rosacea, and neurodermatitis comprising administering the topical emulsion or the topical gel as described herein.

In some embodiments, the disclosure provides for methods and stable topical formulations suitable for the treatment of erythema. The term “erythema” as used herein can refer to the increased/abnormal redness of the skin. In some embodiments, erythema refers to redness patches or localized areas. In some embodiments, the erythema is caused by an inflammatory response. In some embodiments, the erythema is not caused by an inflammatory response, e.g., is caused by an infection (e.g., cellulitis), a cancer, trauma to the skin (e.g., a wound), stress, insect bites, strep throat, fungal diseases, Behcet's disease, pregnancy, inflammatory bowel disease (e.g., Crohn's disease), or is a side effect caused by administration of a drug. In some embodiments, the formulations and methods described herein can be used to reduce erythema by at least one grade, as provided in Table A.

TABLE A Grade Indication None No erythema Mild Faintly detectable erythema, very light pinkness Moderate Dull red, clearly distinguishable Severe Deep, dark red

In some embodiments, the disclosure provides formulations and methods suitable to decrease erythema 10% to 100%, 20% to 100%, 30% to 100%, 40% to 100%, 50% to 100%, 60% to 100%, 70% to 100% or 80% to 100% 7 days, 14 days, 21 days, or 28 days after administration of the formulations described herein. Methods of determining a reduction in erythema are known to the skilled artisan, e.g., in some embodiments the erythema percent change from placebo can be determined by visual inspection, e.g., by a trained medical professional, e.g., by the doctor.

In some embodiments, the disclosure provides a method of reducing erythema in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the erythema is reduced by at least 5% from placebo. In some embodiments, the Montelukast formulation is a topical emulsion or a topical gel as described herein.

In some embodiments, the disclosure provides for stable topical formulation and methods suitable for the treatment of pruritus. The term “pruritus” as used herein can refer to uncomfortable, irritating sensation that makes you want to scratch your skin. In some embodiments, the pruritus is caused by an inflammatory response. In some embodiments, the pruritus is not caused by an inflammatory response, e.g., is caused by an infection (e.g., cellulitis), a cancer, trauma to the skin (e.g., a wound), stress, dry skin, insect bites, or is a side effect caused by administration of a drug. In some embodiments, the formulations and methods described herein can be used to reduce pruritus by at least one grade, as provided in Table B.

TABLE B Grade Indication None No itching Mild Occasional, slight itching, not really bothersome Moderate Constant or intermittent itching that is somewhat bothersome Severe Intense itching that causes pronounced discomfort, disturbing normal activity

In some embodiments, the disclosure provides formulations and methods suitable to decrease pruritus 10% to 100%, 20% to 100%, 30% to 100%, 40% to 100%, 50% to 100%, 60% to 100%, 70% to 100% or 80% to 100% 7 days, 14 days, 21 days, or 28 days after administration of the formulations described herein. Methods of determining a reduction in pruritus are known to the skilled artisan, e.g., in some embodiments the pruritus percent change from placebo can be determined by visual inspection, e.g., by a trained medical professional, e.g., by the doctor.

In some embodiments, the disclosure provides a method of reducing pruritus in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the pruritus is reduced by at least 5% from placebo. In some embodiments, the Montelukast formulation is a topical emulsion or a topical gel as described herein.

In some embodiments, the disclosure provides for topical formulations and methods suitable for the treatment of induration. The term “induration” as used herein can refer to the increase in fibrous elements in skin tissue, thereby increasing the hardness of the skin. In some embodiments, the induration is caused by an inflammatory response. In some embodiments, the induration is not caused by an inflammatory response, e.g., is caused by an infection (e.g., cellulitis), a cancer, trauma to the skin (e.g., a wound), stress, insect bites, or is a side effect caused by administration of a drug. In some embodiments, the formulations and methods described herein can be used to reduce induration by at least one grade, as provided in Table C.

TABLE C Grade Indication None No papulation/induration Mild Barely perceptible elevation Moderate Clearly perceptible elevation but not extensive Severe Marked and extensive elevation

In some embodiments, the disclosure provides formulations and methods suitable to decrease induration 10% to 100%, 20% to 100%, 30% to 100%, 40% to 100%, 50% to 100%, 60% to 100%, 70% to 100% or 80% to 100% 7 days, 14 days, 21 days, or 28 days after administration of the formulations described herein. Methods of determining a decrease in induration are known to the skilled artisan, e.g., in some embodiments the induration percent change from placebo can be determined by visual inspection, e.g., by a trained medical professional, e.g., by the doctor.

In some embodiments, the disclosure provides a method of reducing induration in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the induration is reduced by at least 5% from placebo. In some embodiments, the Montelukast formulation is a topical emulsion or a topical gel as described herein.

In some embodiments, the disclosure provides a topical formulation and methods suitable for the treatment of lichenification. The term “lichenification” refers to the thickening of the skin, or wherein the skin becomes leathery. In some embodiments, the lichenification includes increased markings, e.g., more pronounced wrinkles or creases in the skin. In some embodiments, lichenification includes hyperpigmentation. In some embodiments, the induration is caused by an inflammatory response. In some embodiments, the induration is not caused by an inflammatory response, e.g., is caused by constant scratching/rubbing of the skin (e.g., a repeated motion or as a result of an obsessive-compulsive disorder), an infection (e.g., cellulitis), a cancer, trauma to the skin (e.g., a wound), stress, insect bites, or is a side effect caused by administration of a drug. In some embodiments, the formulations and methods described herein can be used to reduce lichenification by at least one grade, as provided in Table D.

TABLE D Grade Indication None No lichenification Mild Slight thickening of the skin discernible only by touch and with skin marking minimally exaggerated Moderate Definite thickening of the skin with skin marking exaggerated so that they form a visible criss-cross pattern Severe Thickened indurated skin with skin markings visibly portraying an exaggerated criss-cross pattern

In some embodiments, the disclosure provides formulations and methods suitable to decrease lichenification 10% to 100%, 20% to 100%, 30% to 100%, 40% to 100%, 50% to 100%, 60% to 100%, 70% to 100% or 80% to 100% 7 days, 14 days, 21 days, or 28 days after administration of the formulations described herein. Methods of determining a decrease in lichenification are known to the skilled artisan, e.g., in some embodiments the lichenification percent change from placebo can be determined by visual inspection, e.g., by a trained medical professional, e.g., by the doctor.

In some embodiments, the disclosure provides a method of reducing lichenfication in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the lichenfication is reduced by at least 5% from placebo. In some embodiments, the Montelukast formulation is a topical emulsion or a topical gel as described herein.

In some embodiments, the disclosure provides topical formulations and methods suitable for the reducing the Investigator Global Assessment (IGA) score in a subject. The IGA refers to the method as described in Eichenfield L F, et al., J Am Acad Dermatol. 2002; 46(4):495-504. In some embodiments, the formulations and methods described herein can be used to reduce the IGA score by at least one grade, as provided in Table E.

TABLE E Grade Indication Clear No inflammatory signs Almost Clear Just perceptible erythema, and just perceptible papulation/infiltration Mild Mild erythema, and mild papulation/infiltration Moderate Moderate erythema, and moderate papulation/infiltration Severe Disease Severe erythema, and severe papulation/infiltration Very Severe Disease Severe erythema, and severe papulation/infiltration with oozing/crusting

In some embodiments, the disclosure provides formulations and methods suitable to decrease the IGA 10% to 100%, 20% to 100%, 30% to 100%, 40% to 100%, 50% to 100%, 60% to 100%, 70% to 100% or 80% to 100% 7 days, 14 days, 21 days, or 28 days after administration of the formulations described herein. Methods of determining a decrease in IGA are known to the skilled artisan, e.g., in some embodiments the IGA percent change from placebo can be determined by visual inspection, e.g., by a trained medical professional, e.g., by the doctor.

In some embodiments, the disclosure provides a method of reducing the IGA score in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the IGA score is reduced by at least 5% from placebo. In some embodiments, the Montelukast formulation is a topical emulsion or a topical gel as described herein.

In some embodiments, the disclosure provides a topical formulation and methods suitable for the reduction of the Body Surface Area (BSA) affected by the skin conditions described herein, e.g., atopic dermatitis. In some embodiments, the BSA is reduced in a skin condition associated with an inflammatory response. In some embodiments, the BSA is reduced in a skin condition not caused by an inflammatory response.

In some embodiments, the disclosure provides formulations and methods suitable to decrease the BSA 10% to 100%, 20% to 100%, 30% to 100%, 40% to 100%, 50% to 100%, 60% to 100%, 70% to 100% or 80% to 100% 7 days, 14 days, 21 days, or 28 days after administration of the formulations described herein.

In some embodiments, the disclosure provides a method of reducing the BSA score in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, e.g., at least 14 days, wherein the BSA score is reduced by at least 5% from placebo. In some embodiments, the Montelukast formulation is a topical emulsion or a topical gel as described herein.

In some embodiments, administration is accomplished by applying a thin layer of the topical emulsion or topical gel to the affected skin area. The amount of the topical gel or the topical emulsion applied will vary according to several factors, including, but not limited to, the size of the affected area, the severity of the condition, and the concentration of Montelukast in the topical gel or topical emulation.

In some embodiments, the topical gel or topical emulsion are applied one to six times each day, one to four times each day, one to three times each day, one to two times each day. In some embodiments, the topical gel or topical emulsion are applied as needed, or when symptoms appear. In some embodiments, the topical gel or topical emulsion can be applied daily for one day, greater than one day, greater than one week, or greater than one month. In some embodiments, the topical gel or topical emulsion are applied until after the symptoms of the condition being treated have been alleviated. In some embodiments, the topical gel or topical emulsion can be applied before the onset of symptoms. In some embodiments, the topical gel or topical emulsion can be applied every day, every two days, every three days, every four days, twice a week, once a week, etc., as can be determined by the skilled artisan for the treatment of a condition.

In some embodiments, the topical gel or topical emulsions as described herein can be used for treating atopic dermatitis in a human, e.g., a male or a female. In some embodiments, the topical gel or topical emulsions as described herein can be used for treating atopic dermatitis in a human infant (0 to 2 years old), a human child (2 to 12 years old), a human adolescent (12 to 18 years old) or a human adult (older than 18 years old). In some embodiments, the topical gel or topical emulsions as described herein can be used for treating atopic dermatitis in an animal, i.e., non-human, such as a domesticated animal such as a dog, cat, cow, horse, or a zoo animal.

The topical gel or topical emulsion as described herein can be administered topically. When administered by a topical route, the topical gel or topical emulsion is administered in a quantity that is sufficient to cover the affected area with the topical gel or topical emulsion. In some embodiments, the topical gel or topical emulsion is applied to the affected with a layer of approximately 0.01 mm to 5 mm thickness. The topical gel or topical emulsion may be in the form of a cream, gel, patch, foam, lotion, suspension, ointment, topical swab, emulsion, paste, shampoo, solution or spray. The topical gel or topical emulsion can be applied with or without applicator. For example, in some embodiments, the topical gel or topical emulsion is applied with an applicator, e.g., cloth, a swab, a wipe or a patch. In some embodiments, the topical gel or topical emulsion is pre-applied to the applicator, e.g., is a medicated cloth, a medicated swab, a medicated wipe or a medicated patch.

All references cited herein, including patents, patent applications, papers, textbooks and the like, and the references cited therein, to the extent that they are not already, are hereby incorporated herein by reference in their entirety.

EMBODIMENTS Embodiment 1

A topical emulsion comprising

about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; and

about 0.4% to about 4% carbomer;

wherein the particles comprising the Montelukast in the emulsion have D90 of less than about 50 wherein the Montelukast or pharmaceutically acceptable salt thereof is homogeneously dispersed in the emulsion, and wherein the emulsion has a pH of about 3.0 to about 6.5.

Embodiment 2

The topical emulsion of embodiment 1, wherein the particles have D90 of less than about 40 μm.

Embodiment 3

The topical emulsion of embodiment 1, wherein the particles have D90 of less than about 20 μm.

Embodiment 4

The topical emulsion of any one of embodiments 1 to 3, wherein the particles have D90 of greater than about 8 μm.

Embodiment 5

The topical emulsion of any one of embodiments 1 to 3, wherein the particles have D90 of about 10 μm to about 20 μm.

Embodiment 6

The topical emulsion of any one of embodiments 1 to 5, wherein the particles have D50 of less than about 30 μm.

Embodiment 7

The topical emulsion of any one of embodiments 1 to 5, wherein the particles have D50 of less than about 25 μm.

Embodiment 8

The topical emulsion of any one of embodiments 1 to 5, wherein the particles have D50 of less than about 15 μm.

Embodiment 9

The topical emulsion of any one of embodiments 1 to 5, wherein the particles have D50 of less than about 5 μm.

Embodiment 10

The topical emulsion of any one of embodiments 1 to 9, wherein the particles have D10 of less than about 7 μm.

Embodiment 11

The topical emulsion of any one of embodiments 1 to 9, wherein the particles have D10 of greater than about 3 μm.

Embodiment 12

The topical emulsion of any one of embodiments 1 to 11, wherein the average particle size of the particles does not change greater than 10% over a period of 3 months at 25° C.

Embodiment 13

The topical emulsion of any one of embodiments 1 to 12, wherein the Montelukast in the emulsion is about 70% to 95% in the particles as Montelukast acid Form I, and about 5% to about 30% is not in the particles.

Embodiment 14

The topical emulsion of any one of embodiments 1 to 13, wherein the Montelukast in the particles is Montelukast acid Form I.

Embodiment 15

The topical emulsion of any one of embodiments 1 to 14, wherein the emulsion comprises about 4% to about 8% Montelukast.

Embodiment 16

The topical emulsion of any one of embodiments 1 to 15, wherein the emulsion comprises about 40% to about 70% water.

Embodiment 17

The topical emulsion of any one of embodiments 1 to 16, further comprising a penetration enhancer.

Embodiment 18

The topical emulsion of any one of embodiments 1 to 17, wherein the penetration enhancer is DMSO.

Embodiment 19

The topical emulsion of any one of embodiments 1 to 18, wherein the emulsion comprises less than 5% DMSO.

Embodiment 20

The topical emulsion of any one of embodiments 1 to 19, wherein the emulsion comprises less than 3% DMSO.

Embodiment 21

The topical emulsion of any one of embodiments 1 to 20, wherein the emulsion comprises less than 10% alcohol.

Embodiment 22

The topical emulsion of any one of embodiments 1 to 21, wherein the emulsion comprises less than 5% alcohol.

Embodiment 23

The topical emulsion of any one of embodiments 1 to 22, wherein the emulsion comprises less than 2% C₁-C₅ alcohol.

Embodiment 24

The topical emulsion of any one of embodiments 1 to 23, further comprising a preservative, an amphiphilic compound, an emulsifier, a lubricant, or combinations thereof.

Embodiment 25

The topical emulsion of embodiment 24, wherein the preservative is an antioxidant.

Embodiment 26

The topical emulsion of embodiment 25, wherein the antioxidant comprises BHT, BHA or combinations thereof.

Embodiment 27

The topical emulsion of embodiment 24, wherein the amphiphilic compound comprises, oleyl alcohol, polyoxyglycerides, propylene carbonate, propylene glycol, or combinations thereof.

Embodiment 28

The topical emulsion of embodiment 27, wherein the amphiphilic compound is propylene glycol.

Embodiment 29

The topical emulsion of embodiment 24, wherein the emulsifier is a polysorbate.

Embodiment 30

The topical emulsion of embodiment 24, wherein the lubricant is polypropylene glycol stearyl ether.

Embodiment 31

The topical emulsion of any one of embodiments 1 to 30, wherein the total impurities in the emulsion are less than 2% after 12 months at 25° C.

Embodiment 32

The topical emulsion of any one of embodiments 1 to 30, wherein the total impurities in the emulsion are less than 0.5% after 12 months at 25° C.

Embodiment 33

The topical emulsion of any one of embodiments 1 to 32, wherein the sulfoxide impurity in the emulsion is less than 2% after 12 months at 25° C.

Embodiment 34

The topical emulsion of any one of embodiments 1 to 33, wherein the sulfoxide impurity in the emulsion is less than 0.5% after 12 months at 25° C.

Embodiment 35

The topical emulsion of any one of embodiments 1 to 34, wherein the cis-isomer impurity in the emulsion is less than 1% after 12 months at 25° C.

Embodiment 36

The topical emulsion of any one of embodiments 1 to 35, wherein the methylstyrene impurity in the emulsion is less than 0.2% after 12 months at 25° C.

Embodiment 37

The topical emulsion of any one of embodiments 1 to 36, wherein the emulsion has a maximum globule size of less than about 100 μm.

Embodiment 38

The topical emulsion of any one of embodiments 1 to 36, wherein the emulsion has a maximum globule size of less than about 20 μm.

Embodiment 39

A method of treating atopic dermatitis comprising administering the topical emulsion of embodiments 1 to 37.

Embodiment 40

A method of treating erythema comprising administering the topical emulsion of embodiments 1 to 37.

Embodiment 41

A method of treating pruritus comprising administering the topical emulsion of embodiments 1 to 37.

Embodiment 42

A topical gel comprising

-   -   about 0.5% to about 10% Montelukast or pharmaceutically         acceptable salt thereof;     -   about 0.2% to about 8% cellulose polymer; and     -   about 80% to about 95% amphiphilic compound;

wherein the gel comprises less than 4% water.

Embodiment 43

The topical gel of embodiment 42, wherein the gel comprises about 4% to about 8% Montelukast.

Embodiment 44

The topical gel of any one of embodiments 42 to 43, wherein the gel comprises less than 1% C₁-C₅ alcohol.

Embodiment 45

The topical gel of any one of embodiments 42 to 42, wherein the gel does not contain C₁-C₅ alcohol.

Embodiment 46

The topical gel of any one of embodiments 42 to 45, wherein the gel comprises less than 2% water.

Embodiment 47

The topical gel of any one of embodiments 42 to 46, wherein the gel comprises less than 1% water.

Embodiment 48

The topical gel of any one of embodiments 42 to 47, wherein the gel is anhydrous.

Embodiment 49

The topical gel of any one of embodiments 42 to 48, wherein the gel does not comprise a preservative.

Embodiment 50

The topical gel of any one of embodiments 42 to 49, wherein the cellulose polymer comprises hydroxyethylcellulose and hydroxypropyl methylcellulose.

Embodiment 51

The topical gel of any one of embodiments 42 to 50, wherein the cellulose polymer is hydroxypropyl methylcellulose or hydroxypropylcellulose.

Embodiment 52

The topical gel of any one of embodiments 42 to 51, wherein the gel comprises about 2% to about 6% cellulose polymer.

Embodiment 53

The topical gel of any one of embodiments 42 to 52, wherein the gel comprises about 3% to about 4% cellulose polymer.

Embodiment 54

The topical gel of any one of embodiments 42 to 53, wherein the amphiphilic compound comprises oleyl alcohol, polyoxyglycerides, propylene carbonate, propylene glycol, or combinations thereof.

Embodiment 55

The topical gel of embodiment 54, wherein the amphiphilic compound is propylene glycol.

Embodiment 56

The topical gel of embodiment 55, wherein the gel comprises about 85% to about 95% amphiphilic compound.

Embodiment 57

The topical gel of any one of embodiments 42 to 56, wherein total impurities in the gel are less than 2% after 12 months at 25° C.

Embodiment 58

The topical gel of any one of embodiments 42 to 57, wherein the sulfoxide impurity in the gel is less than 2% after 12 months at 25° C.

Embodiment 59

The topical gel of any one of embodiments 42 to 58, wherein the cis-isomer impurity in the gel is less than 0.2% after 12 months at 25° C.

Embodiment 60

The topical gel of any one of embodiments 42 to 59, wherein the methylstyrene impurity in the gel is less than 0.2% after 12 months at 25° C.

Embodiment 61

A method of treating atopic dermatitis comprising administering the topical gel of embodiments 42 to 60.

Embodiment 62

A method of treating erythema comprising administering the topical gel of embodiments 42 to 60.

Embodiment 63

A method of treating pruritus comprising administering the topical gel of embodiments 42 to 60.

Embodiment 64

A method of treating atopic dermatitis comprising topically administering a stable formulation comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof, wherein the formulation is stable for at least 2 weeks.

Embodiment 65

A method of treating erythema comprising topically administering a stable formulation comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof, wherein the formulation is stable for at least 2 weeks

Embodiment 66

A method of treating pruritus comprising topically administering a stable formulation comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof, wherein the formulation is stable for at least 2 weeks.

Embodiment 67

The method of any one of embodiments 64 to 66, wherein the stable formulation is a stable emulsion.

Embodiment 68

The method of any one of embodiments 64 to 66, wherein the stable formulation is a topical gel.

Embodiment 69

A method of treating induration in a subject in need thereof, the method comprising topically administering a topical formulation comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof.

Embodiment 70

A method of treating lichenification in a subject in need thereof, the method comprising topically administering a topical formulation comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof.

Embodiment 71

The method of embodiment 67 or embodiment 68, wherein the formulation is stable for at least 2 weeks.

Embodiment 72

A method of reducing the IGA score in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, wherein the IGA score is reduced by at least 5% from placebo.

Embodiment 73

A method of reducing the BSA score in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, wherein the BSA score is reduced by at least 5% from placebo.

Embodiment 74

A method of reducing erythema in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, wherein the erythema is reduced by at least 5% from placebo.

Embodiment 75

A method of reducing induration in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, wherein the induration is reduced by at least 5% from placebo.

Embodiment 76

A method of reducing lichenfication in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, wherein the lichenfication is reduced by at least 5% from placebo.

Embodiment 77

A method of reducing pruritus in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a Montelukast formulation comprising at least 1% (wt/wt) Montelukast or pharmaceutically acceptable salt thereof for at least 10 days, wherein the pruritus is reduced by at least 5% from placebo.

Embodiment 78

The method of any one of embodiments 72 to 77, wherein the Montelukast formulation is the topical emulsion of any one of embodiments 1 to 38, or the topical gel of any one of embodiments 42 to 60.

Embodiment 79

A stable topical formulation comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; wherein the total impurities resulting from the degradation of Montelukast in the composition are less than 2% after 12, 24 or 36 months at 25° C. and 60% humidity.

Embodiment 80

The stable topical formulation of embodiment 79, wherein the sulfoxide impurity in the formulation is less than 2% after 12, 24 or 36 months at 25° C. and 60% humidity.

Embodiment 81

The stable topical formulation of embodiments 79 or 80, wherein the cis-isomer impurity in the formulation is less than 1% after 12, 24 or 36 months at 25° C. and 60% humidity.

Embodiment 82

The stable topical formulation of any one of embodiments 79 to 81, wherein the methylstyrene impurity in the formulation is less than 0.2% after 12, 24 or 36 months at 25° C. and 60% humidity.

Embodiment 83

The stable topical formulation of any one of embodiments 79 to 82, wherein the Montelukast is homogenously dispersed in the topical formulation for at least about 1 month.

Embodiment 84

The stable topical formulation of any one of embodiments 79 to 83, wherein the formulation is a gel.

Embodiment 85

The stable topical formulation of any one of embodiments 79 to 83, wherein the formulation is an emulsion.

Embodiment 86

The stable topical formulation of embodiment 85, wherein the particle size of particles comprising Montelukast in the emulsion have a D90 of less than about 50 μm and greater than 5 μm,

Embodiment 87

The stable topical formulation of any one of embodiments 85 or 86, wherein the particle size of particles comprising Montelukast in the emulsion does not change greater than 20% over a period of three months at 25° C.,

Embodiment 88

A stable topical formulation comprising about 0.5% to about 10% Montelukast or pharmaceutically acceptable salt thereof; wherein the total impurities resulting from the degradation of Montelukast in the composition are less than 2% after 6 months at 40° C. and 75% humidity.

Embodiment 89

The stable topical formulation of embodiment 88, wherein the sulfoxide impurity in the formulation is less than 2% after 6 months at 40° C. and 75% humidity.

Embodiment 90

The stable topical formulation of embodiments 88 or 89, wherein the cis-isomer impurity in the formulation is less than 1% after 6 months at 40° C. and 75% humidity.

Embodiment 91

The stable topical formulation of any one of embodiments 88 to 90, wherein the methylstyrene impurity in the formulation is less than 0.2% after 6 months at 40° C. and 75% humidity.

EXAMPLES Example 1 Topical Emulsions Without Carbomer

An oil-in-water topical emulsion was made as outlined in Table 3.

TABLE 3 Ingredient % (w/w) Montelukast sodium 5.00 Propylene glycol  5.00-15.00 DMSO  7.00-15.00 Preservative 0.20-1.00 Triglycerides  8.00-14.00 Glycerol Stearate & PEG-100 Stearate  1.00-10.00 Purified Water 50.00-70.00 Cellulose derivative 0.1-1.0 Strong acid q.s. 100%

Since Montelukast is a highly basic compound, titration with a strong acid was needed to lower the pH of the emulsion to a physiological range. The emulsion made according to Table 3 was physically stable, but Montelukast was not chemically stable in the formulation (data not shown).

Example 2 Topical Emulsion With Carbomer

An oil-in-water emulsion formulation was made as outlined in Table 4.

TABLE 4 Ingredient % (w/w) Montelukast sodium  3.00 Alcohol  5.00-10.00 DMSO 10.00 Preservative 0.20-1.00 Polypropylene esters  4.00-14.00 Fatty acid alcohol 2.00-8.00 Chelator 0.05-0.4  Carbomer  1.00 Purified Water 50.00-70.00 Emulsifier 1.00-8.00 100%

Montelukast emulsion was prepared with a carbomer. The emulsion was physically stable.

Example 3 Topical Emulsion Without Ethanol

An oil-in-water emulsion formulation was made as outlined in Table 5.

TABLE 5 Ingredient % (w/w) Montelukast sodium  3.00 DMSO 10.00 Preservative 0.20-1.00 Polypropylene esters  4.00-14.00 Fatty acid alcohol 2.00-8.00 Glyceryl Stearate & PEG-100 Stearate  2.00 Carbomer  1.00 Purified Water 50.00-70.00 Emulsifier 1.00-8.00 100%

Montelukast emulsion was prepared using a carbomer, in the absence of ethanol. The emulsion was physically stable and chemically stable (data not shown).

Example 4 Emulsion With High Concentration of Montelukast

An oil-in-water emulsion formulation was made as outlined in Table 6.

TABLE 6 Ingredient % (w/w) Montelukast sodium 6.50 DMSO 2.50 Preservative 0.20-1.00 Polypropylene esters  4.00-14.00 Fatty acid alcohol 2.00-8.00 Glyceryl Stearate & PEG-100 Stearate 1.00-5.00 Carbomer 1.20 Propylene Glycol 4.00-8.00 Glycerin  5.00-10.00 Weak acid 0.10-1.00 Purified Water 50.00-70.00 Surfactant 1.00-5.00 100%

Montelukast emulsion was prepared with a carbomer. The emulsion also contained 6.5% Montelukast, and remained physically stable with no aggregates or phase separation detected. The emulsion was additionally chemically stable (data not shown).

Example 5 Emulsion With High Concentration of Montelukast

An oil-in-water emulsion formulation was made as outlined in Table 7 comprising different preservatives.

TABLE 7 Ingredient % (w/w) Montelukast sodium 6.50 DMSO 2.50 Preservative 0.5-2.0 Polypropylene esters  4.00-14.00 Fatty acid alcohol 2.00-8.00 Glyceryl Stearate & PEG-100 Stearate 2.00 Carbomer 1.20 Propylene Glycol 6.30 Simple polyol moisturizer  5.00-10.00 Weak acid 0.10-1.00 Purified Water 50.00-70.00 Surfactant 1.00-5.00 100%

Example 6 Stability of Montelukast Emulsion

The stability of the Montelukast emulsion was determined over a period of 3 months. The results are presented in Table 8. Impurity C is sulfoxide impurity, Impurity B is a methyl styrene impurity, and Impurity G is a cis-isomer impurity. RT indicates room temperature conditions, INT indicates intermediate conditions, and ACC indicates accelerated conditions.

TABLE 8 1 month 2 months 3 months Parameter T0 RT INT ACC RT INT ACC RT INT ACC Homogeneity OK OK OK OK OK OK OK OK OK OK Microscopic up to up to up to up to Appearance 20 μm 20 μm 20 μm 20 μm (API Crystals) Assay % 96.8% 95.6% 95.4% 95.5% 95.4% 97.0% 96.8% 95.4% Impurity C 0.08 0.09 0.09 0.11 0.08 0.2 (%) Impurity G 0.08 0.09 0.15 0.17 (%) Impurity B 0.3 0.3 0.3 0.3 0.3 0.28 0.32 0.30 (%) Total (%) 0.41 0.39 0.39 0.41 0.51 0.49 0.60 0.55

Table 8 demonstrates the topical emulsion is physically stable as evidenced by the maintained homogeneity and the lack of Montelukast agglomerates or aggregates. Additionally, the topical emulsion is chemically stable as evidenced by the low levels of sulfoxide impurity, methyl styrene impurity, and cis-isomer impurity.

Example 7 Examples of Various Excipients

To demonstrate the importance of carbomers, and not just the lowering of pH, to the stability of the topical emulsions, various additional oil-in-water topical emulsions were made, using a carbomer, a cellulose derivative, xantham gum, and other means for lowering pH as outlined in Table 9.

TABLE 9 Replace Replace Combination of Without any Replace Example Carbomer Carbomer Low Low concentration polymer. Carbomer with with with with concentration Carbomer and 3% Citric Xanthan Gum. Description Carbomer Klucel Xanthan Gum Carbomer Xanthan Gum acid 3% Citric acid Montelukast 6.50 6.50 6.50 6.50 6.50 6.50 6.50 sodium Glycerin 7.00 7.00 7.00 7.00 7.00 7.00 7.00 DMSO 2.50 2.50 2.50 2.50 2.50 2.50 2.50 PPG-15 Stearyl 8.00 8.00 8.00 8.00 8.00 8.00 8.00 Ether BHT 0.10 0.10 0.10 0.10 0.10 0.10 0.10 Octyl Dodecanol 4.00 4.00 4.00 4.00 4.00 4.00 4.00 Carbomer 1.20 0.30 0.20 Klucel MF 1.00 Xanthan Gum 0.30 0.20 0.30 Propylene Glycol 6.30 6.30 6.30 6.30 6.30 6.30 6.30 Potassium Sorbate 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Benzyl Alcohol 0.50 0.50 0.50 0.50 0.50 0.50 0.50 Citric acid, 0.25 0.52 0.35 0.30 0.30 3.00 3.00 anhydrous Glyceryl 2.00 2.00 2.00 2.00 2.00 2.00 2.00 Stearate & PEG-100 Stearate Polysorbate 60 3.00 3.00 3.00 3.00 3.00 3.00 3.00 Purified Water 58.40 58.33 59.20 59.25 59.15 56.85 56.55 Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00

The stability of each of the emulsions made in Table 9 was determined and is presented in Table 10.

TABLE 10 Replace Combination of Example Replace Carbomer Low Low concentration Without any Replace Carbomer with Carbomer with Xanthan concentration Carbomer and polymer. 3% with Xanthan Description Carbomer with Klucel Gum Carbomer Xanthan Gum Citric acid Gum. 3% Citric acid pH of final formula 5.88 8.97 8.25 8.96 8.98 3.60 3.60 upon preparation pH of final formula 5.85 8.91 9.32 9.06 9.26 3.58 3.61 upon storage (after 4 (after 4 (after 4 (after 3 (after 3 days) days) days) days) days) Phase separation of no Phase separation no no no Agglomeration Agglomeration final formula after 1 day immediately. API immediately. API clusters about 2 cm clusters about 1-2 mm diam. Very sticky. diam. Dispersed in bulk Instability index −0.303; NA* −4.68; −2.58; −4.91; NA*; NA*; sample 1 Instability −0.258  NA* −5.47  −2.53  −5.77 NA* NA* Sample 2: *NA: Instability index cannot be determined due to the agglomeration of the API in the formulation.

The particle size distribution was tested on the emulsions with xantham gum and carbomer. The results were similar: D10=6-7 μm, D50=10 μm, and D90=10-12 μm.

All the emulsion formulations were centrifuged with Lumisizer for 16 h, 4000 rpm at 25° C. and the “instability index” was measured. Formulations with instability index close to zero are considered physically stable formulations. The experiment was performed in duplicates (Table 10).

As demonstrated in Table 10, the topical emulsion with carbomer provided the most stable composition compared to emulsions containing hydroxypropyl cellulose (Klucel), Xanthan gum with citric acid and citric acid alone. The emulsion containing carbomer did not have phase separation, showed lower Instability index as determined by Lumisizer and had pH value compatible with the skin over time (preferably between about 4 to 6).

The data provides evidence that topical emulsion formulations comprising carbomer unexpectedly provide physical stability and pH values compatible with the skin over time.

Example 8 Various Emulsion Formulations

Various carbomer formulations can be prepared, and are outlined in Table 11, for example. However, the disclosure is not limited to those formulations in Table 11.

TABLE 11 Formulation 1 Formulation 2 Formulation 3 Formulation 4 Component % Component % Component % Component % Montelukast 6.5 Montelukast 6.5 Montelukast 6.5 Montelukast 6.5 sodium sodium sodium sodium Carbopol 940 1.2 Carbopol 971P 1.8 Carbopol 934 1.0 Carbopol 941 2.4 NF NF NF Glycerin 8.0 Glycerin 10.0 Glycerin 10.0 Glycerin 10.0 DMSO 4.0 DMSO 1.5 DMSO 2.50 DMSO 3.0 Cyclomethicone 10.0 Dimethicone 7.5 Cyclomethicone 8.0 PPG-15 Stearyl 10.0 Ether Methyl Paraben 0.4 Methyl Paraben 0.4 Methyl Paraben 0.4 Methyl Paraben 0.4 Propyl Paraben 0.1 Propyl Paraben 0.1 Propyl Paraben 0.1 Propyl Paraben 0.1 Propylene 4.0 Propylene 6.0 Oleyl alcohol 4.3 Oleyl alcohol 7.2 Glycol Glycol Benzyl Alcohol 0.25 Propyl alcohol 1.0 Propyl alcohol 0.5 Methanol 0.5 Citric acid, 1.0 Acetic acid 2.5 Citric acid, 0.5 Citric acid, 0.5 anhydrous anhydrous anhydrous Glyceryl 0.25 Glyceryl 0.5 Stearate & PEG- Stearate & 100 Stearate PEG-100 Stearate Polysorbate 80 2.0 Polysorbate 40 0.5 Polysorbate 80 0.75 Polysorbate 60 0.5 Purified Water 62.3 Purified Water 61.7 Purified Water 65.45 Purified Water 58.9 Total 100 100 100 100 Formulation 5 Formulation 6 Formulation 7 Formulation 8 Component % Component % Component % Component % Montelukast 6.5 Montelukast 6.5 Montelukast 6.5 Montelukast 6.5 sodium sodium sodium sodium Carbopol 980 1.2 Carbopol 1342 1.4 Carbopol 974 P 0.6 Carbopol 974P 1.2 NF NF Glycerin 9.0 Glycerin 6.00 Glycerin 10.4 Glycerin 7.0 Polyethylene 4.0 DMSO 2.5 Polyethylene 4.0 DMSO 2.5 glycol glycol Dimethicone 10.0 Cyclomethicone 4.5 PPG-15 Stearyl 6.5 PPG-15 Stearyl 8. Ether Ether Methyl Paraben 0.4 BHA 0.2 BHT 0.2 BHT 0.1 Propyl Paraben 0.1 — — Octyl 4.0 Dodecanol Propylene 4.0 Propylene 8.1 Oleyl alcohol 6.2 Propylene 6.3 Glycol Glycol Glycol Benzyl Alcohol 0.25 Benzyl Alcohol 0.3 Propanol 0.4 Potassium 0.25 Sorbate 60 Citric acid, 1.0 Citric acid, 0.5 Acetic acid 0.4 Benzyl Alcohol 0.5 anhydrous anhydrous Glyceryl 0.25 Glyceryl 2.0 Glyceryl 1.0 Citric acid, 0.25 Stearate & Stearate & PEG- Stearate & anhydrous PEG-100 100 Stearate PEG-100 Stearate Stearate Polysorbate 60 2.0 Polysorbate 80 0.1 Polysorbate 40 0.5 Glyceryl 2.0 Stearate & PEG-100 Stearate Octyl 4.0 Octyl 4.00 Polysorbate 60 3.0 Dodecanol Dodecanol Purified Water 57.3 Purified Water 63.9 Purified Water 63.3 Purified Water 58.4 Total 100 100 100 Total 100 Formulation 9 Formulation 10 Formulation 11 Formulation 12 Component % Component % Component % Component % Montelukast 6.5 Montelukast 6.5 Montelukast 6.5 Montelukast 6.5 sodium sodium sodium sodium Carbopol 2.0 Carbopol 5984 2.4 Carbopol 974 P 3.5 Carbopol 974P 2.4 981NF EP Glycerin 9.0 Glycerin 7.0 Glycerin 6.0 Glycerin 7.0 Polyethylene 4.0 Diethylene 4.0 Diethylene 4.0 Diethylene 2.5 glycol glycol glycol glycol monoethyl ether monoethyl monoethyl ether ether PPG-15 Stearyl 8.0 Cyclomethicone 6.0 Dimethicone 5.3 PPG-15 Stearyl 10.0 Ether Ether Methyl Paraben 0.40 BHA 0.1 BHA 0.1 BHT 0.1 Propyl Paraben 0.10 BHT 0.1 BHT 0.1 Octyl 8.0 Dodecanol Propylene 4.00 Oleyl alcohol 7.0 Propylene 5.0 Propylene 6.3 Glycol Glycol Glycol Benzyl Alcohol 0.25 Benzyl Alcohol 1.5 Propanol 1.0 Potassium 0.25 Sorbate 60 Citric acid, 1.0 Acetic acid 0.75 Acetic acid 0.5 Benzyl Alcohol 0.5 anhydrous Glyceryl 0.25 Glyceryl 4.0 Glyceryl 3.0 Citric acid, 0.25 Stearate & Stearate & PEG- Stearate & anhydrous PEG-100 100 Stearate PEG-100 Stearate Stearate Polysorbate 60 2.0 Glyceryl 2.0 Stearate & PEG-100 Stearate Purified Water 62.5 Purified Water 60.65 Purified Water 65.0 Purified Water 54.2 Total 100 100 100 Total 100

Example 9 Topical Gel Formulation

A topical gel was made as outlined in Table 12.

TABLE 12 Ingredient % (w/w) Montelukast sodium 6.50 Fatty acid alcohol  5.00-10.00 Propylene Glycol 70.00-92.00 Cellulose derivative 1.00-6.00 Emulsifier 1.00-6.00 100%

The topical gel of Table 12 was not chemically stable, as evidenced by the quick formation of impurities as demonstrated in Table 13.

TABLE 13 Impurity C (sulfoxide impurity) (%) T₀ 1 month RT 1 month ACC 2 months ACC 6 months ACC 0.14 0.20 0.40 0.61 2.03

Additionally, the topical gel was not physically stable. Although the Montelukast was soluble at T₀, the Montelukast started precipitating in the gel after 2 months at accelerated conditions (data not shown).

Example 10 Topical Gel Formulation

A topical gel was made as outlined in Table 14, wherein a preservative BHA was added in an attempt to increase chemical stability.

TABLE 14 Ingredient % (w/w) Montelukast sodium 6.50 BHA 0.5-2.5 Fatty acid alcohol  5.00-10.00 Propylene Glycol 70.00-92.00 Cellulose derivative 1.00-6.00 Emulsifier 1.00-6.00 100%

Additional of the preservative BHA did not improve stability, as evidenced by the formation of impurities as demonstrated in Table 15.

Table 15.

TABLE 15 Impurity C (sulfoxide impurity) (%) 1 month 1 month 2 months 6 months T₀ RT ACC ACC ACC 0.25 0.49 0.97 1.53 6.65

Additionally, the topical gel was not physically stable. Although the Montelukast was soluble at T₀, the Montelukast started precipitating in the gel after 1 month (data not shown).

Example 11 Topical Emulsion With Increased Montelukast

A topical emulsion was made as outlined in Table 16.

TABLE 16 Ingredient % (w/w) Montelukast sodium 8.00 Glycerin  5.00-10.00 DMSO 2.50 Preservative 0.1-0.3 Polypropylene esters  4.00-14.00 Long-chain fatty alcohol 2.00-6.00 Carbomer 1.00 Propylene Glycol 4.00-8.00 Purified Water 50.00-70.00 Weak acid 0.10-1.00 Acrylamide/sodium acryloyldimethyl taurate copolymer 3.00-5.00

The topical emulsion of Table 16 was shown to be physically stable for at least three months under standard conditions (data not shown).

Example 12 Topical Gel Formulation

A topical gel was prepared as outlined in Table 17,

TABLE 17 Ingredient % (w/w) Montelukast sodium 6.5 Propylene Glycol 83.5%-92.5% Cellulose derivative  1.00-10.00 100%

The topical gel as formulated in Table 17 was shown to be both chemically and physically stable over an extended period of time as shown in Table 18.

TABLE 18 1 month 2 months 3 months Parameter T0 RT INT ACC RT INT ACC RT INT ACC Homogeneity OK OK OK OK OK OK OK OK OK OK Microscopic No No No No No No No Appearance (API Crystals) Assay % 96.5 96.8 97.2 96.7 101.2 100.3 100.7 98.4 98.7 98.0 (90-110) Impurity C- 0.08 0.08 0.1 0.11 0.12 0.13 0.19 0.16 0.17 0.26 sulfoxide (%) Impurity G-cis 0.05 0.06 0.06 0.05 isomer (%) Impurity B- 0.08 0.08 0.08 0.08 0.08 0.09 0.09 0.1 0.13 0.11 methyl styrene (%) Total 0.26 0.41 0.47 0.66 0.35 0.37 0.47 0.35 0.53 0.67 Impurities (%)

Thus, the topical gel of the present disclosure provides for physical stability as well as chemical stability.

Example 13 Stability Comparison of Topical Emulsion and Topical Gel to Other Emulsions

Applicant compared the topical emulsion of the present disclosure to the emulsions reported in WO 2019/007356 (Example 8 and Example 9). The topical emulsions disclosed in WO 2019/007356 (Example 8 and Example 9) do not comprise a carbomer as featured in the present disclosure. The results presented in Table 19 are for T=0.

TABLE 19 Topical Emulsion WO 2019/007356 WO 2019/007356 (Carbomer Parameter example 8 example 9 Formulation) Topical Gel Homogeneity No phase separation. No phase separation. Homogeneous Homogeneous Grainy consistency. Grainy consistency. After 24 hours After 24 hours non-homogeneous non-homogeneous Assay % 97.9 94.4 96.8 96.5 (90-110%) Impurity C 0.50** 0.75** 0.08 0.08 Sulfoxide (%) Total 0.80 1.47** 0.41 0.26 Impurities (%) **indicates out of desired specification

Table 19 demonstrates the topical emulsions disclosed in WO 2019/007356 are not physically stable even after 24 hours as evidenced by the non-homogeneous consistency. Additionally, the topical emulsions disclosed in WO 2019/007356 are not chemically stable as evidenced by the appearance of impurities.

Example 14 Stability Comparison of Topical Emulsion to Other Topical Solutions

Applicant compared the topical emulsion of the present disclosure (Carbomer Formulation) to the solutions reported in WO 2010/104281 (Table 1 and Table 2). The solutions in WO 2010/104281 were prepare by dissolving Montelukast in a solution comprising ethanol:propylene glycol at a ratio of 7:3. The Montelukast was present at 0.5%, 1%, 2% (Table 1) or 14%. 26% or 36% (Table 2). The results of WO 2010/104281 and the present disclosure (Carbomer Formulation) are presented in Table 20.

TABLE 20 Analytical Parameter, % T0 1 month RT 1 month ACC WO 2010/104281 Assay (90-110%) 98.1 96.4 95.4 Topical solution Sulfoxide Impurity (%) NA 1.99 2.87 Cis-isomer Impurity (%) 0.08 0.93 1.19 Methylstyrene Impurity (%) 0.3 0.3 0.3 Total Impurity (%) 0.38 3.2 4.4 Carbomer Assay (90-110%) 96.3 100.7 100.9 Formulation Sulfoxide Impurity (%) 0.07 0.12 0.14 Cis-isomer Impurity (%) 0.12 <0.05 <0.05 Methylstyrene Impurity (%) 0.10 0.08 0.08 Total Impurity (%) 0.35 0.20 0.22

Table 20 provides additional support that topical emulsions comprising Montelukast and carbomers are more stable than topical formulations previously reported, as evidenced by the low levels of sulfoxide impurity, methyl styrene impurity, and cis-isomer impurity.

Example 15 Long Term Stability Analysis

As demonstrated previously in Example 6, Table 8, the topical emulsion of the present disclosure provides increased stability for up to three months, even under accelerated storage conditions. As demonstrated previously in Example 12, Table 18, the topical gel of the present disclosure provides increased stability for up to three months, even under accelerated storage conditions.

The stability of the topical emulsion of Example 5 and the topical gel of Example 12 was further investigated for up to 12 months. The 6 month and the 9 month stability data are also presented in Table 21.

TABLE 21 Analytical 24 Parameter, 6 months 9 months 12 months months % ACC INT RT INT RT INT RT RT Emulsion Assay 99.9 98.0 98.1 98.5 99.1 104.4 104.9 100.6 formulation (90-110) Sulfoxide 0.26 0.19 0.16 0.20 0.17 0.28 0.22 0.26 Impurity (%) Cis-isomer <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.1 Impurity (%) Methylstyrene 0.07 0.07 0.07 0.10 0.09 0.07 0.07 <0.1 Impurity (%) Total 0.40 0.32 0.28 0.32 0.31 0.41 0.4 0.26 Impurity (%) Gel Assay 95.2 95.2 95.7 95.8 97.9 103.6 104.1 ND formulation (90-110) Sulfoxide 0.29 0.17 0.15 0.21 0.16 0.26 0.2 ND Impurity (%) Cis-isomer <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 0.07 ND Impurity (%) Methylstyrene 0.10 0.09 0.09 0.09 0.09 0.09 0.09 ND Impurity (%) Total 0.61 0.49 0.35 0.54 0.39 0.78 0.63 ND Impurity (%) ND-not determined

Table 21 provides evidence that the topical emulsion and the topical gel as provided herein are chemically stable for up to 12 months in both RT and INT conditions.

Without being bound by any theory, in some embodiments the carbomer contributes to physiochemical stability of the formulation.

Example 16 Emulsion With Reduced Globule Size

The formulations containing Carbomer used in the globule size analysis appear for example in Table 9- and in Table 11. The comparative formulation (Example 14 as disclosed in U.S. Pat. No. 10,548,837) is as found in Table 22:

TABLE 22 Comparative formulation: Montelukast in a cream formulation Ingredient % W/W Montelukast sodium   5% Propylene glycol   10% DMSO   10% Methylparaben  0.3% Propylparaben  0.1% BHT  0.1% MCT   10% Glyceryl Stearate &   5% PEG-100 Stearate Purified water 59.1% Natrosol 250 HEC 0.30% HHX EDTA  0.1% HCl (10% sol) q.s. Sample Preparation Procedure:

Prior to performing the globule size analysis of a sample, a clean glass microscope slide and cover slip (that later will be used for the sample) were placed on the microscope and their cleanness was assess under magnifying lens. A sample from an emulsion without carbomer (Comparative formulation above) and a sample from an emulsion comprising carbomer (Table 9) was taken from 2-3 different areas in the container in which they were stored (sample from the depth of the product not from the surface) and transferred onto a microscope slide. A cover slip was placed over the sample and pressed gently in order to spread the sample thoroughly.

A magnification of ×50 was used. The sample was focused in manner that properly showed the globule particles and crystals.

Globule Assessment Using Nikon Eclipse ciPOL Microscope Under non Polarized Light

Two samples were examined under the microscope using suitable magnification (suitable objective size). Two fields of view were evaluated for each sample. Air, oil and water globules were distinguished from each other. The largest globules in a field of view were measured and the size was recorded in the report. Using this method, it was determined that the sample from an emulsion without carbomer (Comparative formulation) had a maximum globule size of 458 μm, while the sample from an emulsion comprising carbomer (Table 9) had a maximum globule size of 8 μm.

The correlation between the type of polymer and the globule size of various formulation batches prepared by two different processes was determined. The results are presented in Table 23.

TABLE 23 Globule % size Batch Prototype polymer (um) 1 Example 14 as disclosed in U.S. Pt. No. HEC Up to 458 10,548,837 (o/w emulsion) 0.3% 2 o/w emulsion with Carbomer - first batch Carbomer Up to 8 1.2% 3 o/w emulsion with Carbomer - second Carbomer Up to 5 batch 1.2% 4 o/w emulsion with lower concentration of Carbomer Up to 16 Carbomer 0.4% HEC = hydroxyethyl cellulose

Table 23 demonstrates that globule size of formulations depends on type of polymer and its concentration in the formulations.

Conclusions:

Emulsion formulations with carbomer provides a smaller globule size relative to emulsion formulations with cellulose at almost similar concentration. Small globule size of the emulsion of the invention can be advantageous with respect to formulation long-term stability. Droplet size is one of the important characteristic of the topical formulation that contributes to the physical stability of dermal and cosmetic products. The small droplet size prevents the droplet coalescence and sedimentation against gravitational force.

Example 17 Double Blind Clinical Study of 6.5% Montelukast Topical Cream

A multi-center, double-blind, randomized, placebo-controlled study using a Montelukast cream as described herein (6.5%) was conducted. Patients experiencing mild or moderate atopic dermatitis were administered to one arm the cream 2 times a day for 28 days. The opposing arm was administered a vehicle placebo. The percent change from placebo as measured by six different endpoints Investigator Global Assessment (IGA), Body Surface Area (BSA), erythema, induration, lichenification, and pruritus was determined on days 0, 14 and 28, and compared to a vehicle placebo. The results presented in Table 24 demonstrate that the test product achieved significant improvement over vehicle in all of the above six endpoints, with over 10% significant improvement observed as early as 14 days into the treatment with Montelukast cream of the invention. The results of the clinical study also revealed that safety was not compromised even with a 28 days treatment with topical Montelukast. Specifically, at least 60% of the patients reported either absent or mild Dryness and Scaling at week 4 of treatment, and at least 60% of the patients reported absent of Erosion at week 4 of treatment.

TABLE 24 Statistically significant treatment effect (active versus placebo) Clinical parameter Week 2 Week 4 IGA Δ20%*** Δ20%*** % BSA Affected Δ25%*** Δ20%*** Erythema Δ30%*** Δ30%*** Induration Δ20%*  Δ15%   Lichenification Δ15%   Δ30%*** Pruritis Δ20%**  Δ20%*** *p < 0.05 **p < 0.01 ***p < 0.001

All references cited herein, including patents, patent applications, papers, textbooks and the like, and the references cited therein, to the extent that they are not already, are hereby incorporated herein by reference in their entirety. 

What is claimed is:
 1. A method of treating atopic dermatitis, erythema, pruritus or combinations thereof comprising topically administering a stable formulation comprising about 0.5% to about 10% montelukast or pharmaceutically acceptable salt thereof, wherein the formulation is stable for at least 2 weeks.
 2. The method of claim 1, wherein particles comprising the montelukast in the formulation have D₉₀ of less than about 50 μm.
 3. The method of claim 1, wherein the particles have D₅₀ of less than about 30 μm.
 4. The method of claim 1, wherein the formulation has a pH of about 3.0 to about 6.5.
 5. The method of claim 1, wherein the average particle size of the particles does not change greater than 10% over a period of 3 months at 25° C.
 6. The method of claim 1, wherein the formulation comprises about 4% to about 8% montelukast.
 7. The method of claim 1, wherein the formulation comprises about 40% to about 70% water.
 8. The method of claim 1, wherein the formulation comprises less than 10% alcohol.
 9. The method of claim 1, wherein the formulation comprises less than 2% C₁-C₅ alcohol.
 10. The method of claim 1, wherein the formulation further comprises a preservative, an amphiphilic compound, an emulsifier, a lubricant, or combinations thereof.
 11. The method of claim 10, wherein the preservative is an antioxidant.
 12. The method of claim 11, wherein the antioxidant comprises butylated hydroxy toluene (BHT), butylated hydroxy anisole (BHA) or combinations thereof.
 13. The method of claim 10, wherein the amphiphilic compound comprises, oleyl alcohol, polyoxyglycerides, propylene carbonate, propylene glycol, or combinations thereof.
 14. The method of claim 13, wherein the amphiphilic compound is propylene glycol.
 15. The method of claim 10, wherein the emulsifier is a polysorbate.
 16. The method of claim 10, wherein the lubricant is polypropylene glycol stearyl ether.
 17. The method of claim 1, wherein total impurities in the formulation is less than 2% after 12 months at 25° C.
 18. The method of claim 1, wherein a sulfoxide impurity in the formulation is less than 2% after 12 months at 25° C. and 60% humidity, wherein a cis-isomer impurity in the formulation is less than 1% after 12 months at 25° C. and 60% humidity, and wherein a methylstyrene impurity in the formulation is less than 0.2% after 12 months at 25° C. and 60% humidity.
 19. The method of claim 1, wherein the formulation has a maximum globule size of less than about 100 μm.
 20. The method of claim 1, the formulation has a maximum globule size of less than about 20 μm.
 21. The method of claim 1, wherein the total impurities resulting from the degradation of montelukast in the formulation is less than 2% after 6 months at 40° C. and 75% humidity.
 22. The method of claim 1, wherein a sulfoxide impurity in the formulation is less than 2% after 6 months at 40° C. and 75% humidity, wherein a cis-isomer impurity in the formulation is less than 1% after 6 months at 40° C. and 75% humidity, and wherein a methylstyrene impurity in the formulation is less than 0.2% after 6 months at 40° C. and 75% humidity.
 23. A method of reducing Investigator Global Assessment (IGA score or Body Surface Area (BSA) score in a subject suffering from atopic dermatitis, the method comprising topically administering to the subject a montelukast formulation comprising at least 1% (wt/wt) montelukast or pharmaceutically acceptable salt thereof for at least 10 days, wherein the IGA score or the BSA score is reduced by at least 5% from placebo. 